Plan of the study
Contents
Part A — The text of the Mechaber
1. The text of the Shulchan Aruch — the 4 seifim of the Mechaber
Part B — General context and key concepts
2. The general context — why this siman, what is the question?
3. First key concept — the 3 days rule (ג' ימים קודם השבת)
4. Second key concept — דבר מצוה vs דבר רשות
5. Third key concept — פוסק עמו שישבות (posek imo sheyishbos)
6. Why 3 days? The three classical pirushim
Part C — Pedagogical study seif by seif
Part D — The position of the Rema, modern cases and synthesis
11. The position of the Rema — what changes for an Ashkenazi
12. Modern practical cases — flights, cruises, trains, overnight buses
13. Practical synthesis and rules to remember
14. Comprehension questions
Section 1 — The text of the Shulchan Aruch
The 4 seifim of Rav Yosef Karo
Siman רמ״ח of the Mechaber contains 4 seifim that codify the halachos of traveling by ship or by shayara (caravan) in the days before Shabbos. The hagahos of the Rema (Poland, 1572) are woven into the standard text and marked by הג"ה.
Seif Alef — The base rule
מֻתָּר לְהַפְלִיג בִּסְפִינָה אֲפִלּוּ בְּעֶרֶב שַׁבָּת אִם הוֹלֵךְ לִדְבַר מִצְוָה, וּפוֹסֵק עִמּוֹ שֶׁיִּשְׁבּוֹת. וְאִם אַחַר כָּךְ לֹא יִשְׁבּוֹת — אֵין בְּכָךְ כְּלוּם. אֲבָל לִדְבַר הָרְשׁוּת אֵין מַפְלִיגִין בִּסְפִינָה בְּפָחוֹת מִג' יָמִים קוֹדֶם הַשַּׁבָּת. הגה: אֲבָל קוֹדֶם שְׁלֹשָׁה יָמִים — שָׁרֵי, אֲפִלּוּ בִּסְפִינָה שֶׁמּוֹשְׁכִין אוֹתוֹ עַל יְדֵי בְּהֵמוֹת, אֲפִלּוּ אֵין בְּגֹבַהּ הַמַּיִם י' טְפָחִים [מהרי"ק שורש מ"ה], וַאֲפִלּוּ בְּמָקוֹם שֶׁיִּצְטָרֵךְ הַיִּשְׂרָאֵל לַעֲשׂוֹת אַחַר כָּךְ מְלָאכָה בְּשַׁבָּת לְהוֹלִיךְ הַסְּפִינָה [ריב"ש סי' קנ"ב]. וְאִם הוּא דֶּרֶךְ מוּעָט כְּמוֹ מִצּוֹר לְצִידוֹן, שֶׁאֵין בֵּינֵיהֶם כִּי אִם מַהֲלַךְ יוֹם אֶחָד — מֻתָּר לְהַפְלִיג בְּעֶרֶב שַׁבָּת בַּבֹּקֶר, מִפְּנֵי שֶׁאֶפְשָׁר שֶׁיַּגִּיעַ שָׁם קוֹדֶם הַשַּׁבָּת. וּמָקוֹם שֶׁנָּהֲגוּ שֶׁלֹּא לְהַפְלִיג בְּעֶרֶב שַׁבָּת כְּלָל, אֲפִלּוּ דֶּרֶךְ מוּעָט — אֵין מַפְלִיגִין.
It is muttar to embark on a ship even on erev Shabbos if one travels for a devar mitzvah, and one is posek imo sheyishbos (settles with the boatman that he will rest on Shabbos). And if afterwards the boatman does not stop — it is no kashya at all. But for a devar reshus, one does not embark on a ship within 3 days before Shabbos. Hagahah of the Rema: But more than three days before Shabbos it is permitted — even on a ship pulled by animals, even where the water is not ten tefachim deep [Maharik, shoresh 45], and even where the Yisrael will afterwards need to perform a melachah on Shabbos to move the ship along [Rivash, siman 152]. The Mechaber continues: if the route is short — such as from Tzor to Tzidon, which is no more than a single day's journey — one may embark on erev Shabbos in the morning, since one can arrive before Shabbos. And in a place where the custom is not to embark on erev Shabbos at all, even for a short route — one does not embark.
The central idea of Seif Alef: "one does not embark within the 3 days preceding Shabbos" — with two major exceptions: (1) if it is for a mitzvah (with the convention to stop on Shabbos); (2) if the distance is short and one can arrive before Shabbos.
Seif Beis — Why 3 days? Salt sea vs river
הָא דְּאֵין מַפְלִיגִין בִּסְפִינָה בְּפָחוֹת מִשְּׁלֹשָׁה יָמִים קוֹדֶם הַשַּׁבָּת — הַטַּעַם מִשּׁוּם עוֹנֶג שַׁבָּת, שֶׁכָּל שְׁלֹשָׁה יָמִים הָרִאשׁוֹנִים יֵשׁ לָהֶם צַעַר וּבִלְבּוּל. וְדַוְקָא לְמַפְלִיגִים בְּמַיִם הַמְּלוּחִים. אֲבָל בִּנְהָרוֹת אֵין שׁוּם צַעַר לְמַפְלִיגִים בָּהֶם — וּלְפִיכָךְ מֻתָּר לְהַפְלִיג בָּהֶם אֲפִלּוּ בְּעֶרֶב שַׁבָּת, וְהוּא שֶׁלֹּא יְהֵא יָדוּעַ לָנוּ שֶׁאֵין בְּעָמְקָם עֲשָׂרָה טְפָחִים. אֲבָל בְּמָקוֹם שֶׁיָּדוּעַ לָנוּ שֶׁמִּקַּרְקַע הַסְּפִינָה לְקַרְקַע הַנָּהָר פָּחוֹת מֵעֲשָׂרָה טְפָחִים — אָסוּר (לָצֵאת חוּץ לַתְּחוּם) מִשּׁוּם אִסּוּר תְּחוּמִין. הגה: וְכֵן בִּסְפִינָה שֶׁיִּצְטָרֵךְ הַיִּשְׂרָאֵל לָבֹא לִידֵי מְלָאכָה בְּשַׁבָּת — אָסוּר לִיכָּנֵס בָּהּ שְׁלֹשָׁה יָמִים קוֹדֶם הַשַּׁבָּת, אֲפִלּוּ הֵם נְהָרוֹת הַנּוֹבְעִים וְהוּא לְמַעְלָה מֵעֲשָׂרָה (ריב"ש סי' קנ"ב מהרי"ק). אֲבָל אֵין אִסּוּר בְּמַה שֶּׁהַבְּהֵמוֹת מוֹשְׁכוֹת הַסְּפִינָה בִּשְׂפַת הַנָּהָר, וְלֹא דָּמֵי לַהֲלִיכָה בְּקָרוֹן שֶׁאָסוּר.
The reason for the 3-days rule is oneg Shabbos: during the first 3 days at sea, one suffers from seasickness (tza'ar u-bilbul). This applies only to the salty sea. On rivers there is no tza'ar for those sailing on them — therefore one may embark even on erev Shabbos, provided it is not known to us that their depth is less than ten tefachim. But in a place where we know that there are less than ten tefachim between the bottom of the ship and the riverbed — it is assur (to go beyond the techum), because of issur techumin. Hagahah of the Rema: And likewise, on a ship where the Yisrael will come to need to do a melachah on Shabbos, it is assur to board it within the three days before Shabbos — even if these are flowing rivers and the ship is more than ten tefachim above the riverbed [Rivash siman 152, Maharik]. But there is no issur in the animals pulling the ship along the riverbank — and it is not comparable to traveling in a wagon, which is assur.
Seif Gimel — Kanah shevisah: boarding before Shabbos
הֵיכָא דְּמֻתָּר לְהַפְלִיג מֵעֶרֶב שַׁבָּת, אִם נִכְנַס בַּסְּפִינָה מֵעֶרֶב שַׁבָּת וְקָנָה בָהּ שְׁבִיתָה — אַף עַל פִּי שֶׁמַּפְלֶגֶת בְּשַׁבָּת מֻתָּר, וְהוּא שֶׁלֹּא יֵצֵא מֵהַסְּפִינָה מֵעֵת שֶׁקָּנָה שְׁבִיתָה. הגה: וְיֵשׁ אוֹמְרִים דַּאֲפִלּוּ יָצָא מִן הַסְּפִינָה שָׁרֵי, דְּמֵאַחַר שֶׁקָּנָה בָהּ שְׁבִיתָה מֵעֶרֶב שַׁבָּת — מֻתָּר אַחַר כָּךְ לִיכָּנֵס בָּהּ בְּשַׁבָּת וּלְהַפְלִיג. וְיֵשׁ אוֹמְרִים שֶׁעוֹשִׂין קִדּוּשׁ בַּסְּפִינָה וְאַחַר כָּךְ חוֹזְרִים לְבֵיתָם וְלָנִים שָׁם, וּלְמָחָר חוֹזְרִין לַסְּפִינָה וּמַפְלִיגִין. כֵּן נָהֲגוּ בִּקְצָת מְקוֹמוֹת וְאֵין לִמְחוֹת (ר"ן פ"ק דשבת וריב"ש סי' י"ז קכ"א קכ"ב), וְעַיֵּן לְקַמָּן סִי' של"ט ות"ד.
Wherever it is permitted to embark on erev Shabbos, if one entered the ship on erev Shabbos and was kanah shevisah in it — even if the ship sets sail on Shabbos itself, it is muttar, provided he did not leave the ship from the moment he was kanah shevisah. Hagahah of the Rema: Some say that even if he left the ship it is permitted: since he was kanah shevisah in it on erev Shabbos, he may afterwards re-enter it on Shabbos and set sail. And some say that one makes Kiddush on the ship, then returns home and sleeps there, and the next day returns to the ship and sets sail; such is the minhag in some places, and one should not protest [Ran, first perek of Shabbos; Rivash simanim 17, 121, 122]. And see further siman 339 and siman 404.
Seif Daled — Shayara in the desert + aliyah
הַיּוֹצְאִים בְּשַׁיָּרָא בַּמִּדְבָּר וְהַכֹּל יוֹדְעִים שֶׁהֵם צְרִיכִים לְחַלֵּל שַׁבָּת, כִּי מִפְּנֵי הַסַּכָּנָה לֹא יוּכְלוּ לְעַכֵּב בַּמִּדְבָּר בְּשַׁבָּת לְבַדָּם — ג' יָמִים קוֹדֶם שַׁבָּת אֲסוּרִים לָצֵאת, וּבְיוֹם רִאשׁוֹן וּבַשֵּׁנִי וּבַשְּׁלִישִׁי מֻתָּר לָצֵאת. וְאִם אַחַר כָּךְ יֶאֱרַע לוֹ סַכָּנָה וְיִצְטָרֵךְ לְחַלֵּל שַׁבָּת מִפְּנֵי פִּקּוּחַ נֶפֶשׁ — מֻתָּר, וְאֵין כָּאן חִלּוּל. וְהָעוֹלֶה לְאֶרֶץ יִשְׂרָאֵל, אִם נִזְדַּמְּנָה לוֹ שַׁיָּרָא אֲפִלּוּ בְּעֶרֶב שַׁבָּת — כֵּיוָן דִּדְבַר מִצְוָה הִיא יָכוֹל לִפְרֹשׁ, וּפוֹסֵק עִמָּהֶם לִשְׁבּוֹת. וְאִם אַחַר שֶׁיִּהְיוּ בַּמִּדְבָּר לֹא יִרְצוּ לִשְׁבּוֹת עִמּוֹ — יָכוֹל לָלֶכֶת עִמָּהֶם חוּץ לַתְּחוּם מִפְּנֵי פִּקּוּחַ נֶפֶשׁ. וְאִם נִכְנַס לְעִיר אַחַת בְּשַׁבָּת — מְהַלֵּךְ אֶת כֻּלָּהּ, וַאֲפִלּוּ הִנִּיחוּהוּ מִחוּץ לָעִיר וְרוֹצֶה לִיכָּנֵס לָעִיר מֻתָּר, דְּכֵיוָן דְּלִדְבַר מִצְוָה נְפַק — יֵשׁ לוֹ אַלְפַּיִם אַמָּה לְכָל רוּחַ.
For those who set out with a shayara into the desert — where everyone knows they will have to be mechalel Shabbos, for because of the sakanah they will not be able to stay behind alone in the desert on Shabbos — within 3 days before Shabbos it is forbidden to leave; but on Sunday, Monday and Tuesday (days 1, 2, 3) it is muttar to leave. And if afterwards a sakanah befalls him and he must be mechalel Shabbos because of pikuach nefesh — it is muttar, and there is no chilul here. For one who is doing aliyah l'Eretz Yisrael, if a shayara presents itself even on erev Shabbos — since it is a devar mitzvah, he may set out; and he stipulates with them that they will rest on Shabbos. And if, once they are in the desert, they do not want to rest with him — he may go with them beyond the techum, because of pikuach nefesh. And if he enters a city on Shabbos — he may walk through all of it; and even if they left him outside the city and he wants to enter it — it is muttar: since he set out for a devar mitzvah, he has 2000 amos in every direction.
Hagahah of the Rema — extending devar mitzvah (Rabbeinu Tam)
הגה: יֵשׁ אוֹמְרִים שֶׁכָּל מָקוֹם שֶׁאָדָם הוֹלֵךְ לִסְחוֹרָה אוֹ לִרְאוֹת פְּנֵי חֲבֵרוֹ — חָשׁוּב הַכֹּל דְּבַר מִצְוָה, וְאֵינוֹ חָשׁוּב דְּבַר הָרְשׁוּת רַק כְּשֶׁהוֹלֵךְ לְטַיֵּל. וְעַל כֵּן נָהֲגוּ בִּקְצָת מְקוֹמוֹת לְהָקֵל בְּעִנְיַן הַפְלָגַת הַסְּפִינוֹת וַהֲלִיכַת שַׁיָּרָא תּוֹךְ שְׁלֹשָׁה יָמִים, כִּי חוֹשְׁבִים הַכֹּל לִדְבַר מִצְוָה, וְאֵין לִמְחוֹת בְּיָדָן הוֹאִיל וְיֵשׁ לָהֶם עַל מִי שֶׁיִּסְמֹכוּ.
Hagahah of the Rema (citing Rabbeinu Tam): Anywhere a person travels — for business or to greet his friend — counts as a devar mitzvah. Only traveling purely for sightseeing is devar reshus. And therefore the minhag in some places is to be lenient regarding setting sail by ship and traveling with a shayara within the three days, since they consider everything a devar mitzvah — and one should not protest, since they have on whom to rely.
Section 2 — General context
Why this siman, what is the question?
What is this siman about?
Our siman deals with a very concrete situation: when may one undertake a journey that will spill over into Shabbos — whether by ship, by shayara (caravan), or in our modern applications (flight, train, cruise)?
The fundamental question: knowing that the journey will continue on Shabbos, may one set out on it? Or does it violate the issur of "לא תעשה כל מלאכה" by the very fact that one is in motion on Shabbos?
The talmudic source — the braysa of Shabbos 19a
The entire siman derives from a classical braysa cited in Shabbos 19a:
תָּנוּ רַבָּנָן: אֵין מַפְלִיגִין בִּסְפִינָה פָּחוֹת מִג' יָמִים קוֹדֶם לְשַׁבָּת. בַּמֶּה דְּבָרִים אֲמוּרִים? לִדְבַר הָרְשׁוּת. אֲבָל לִדְבַר מִצְוָה — שַׁפִּיר דָּמֵי, וּפוֹסֵק עִמּוֹ עַל מְנָת לִשְׁבּוֹת. רַבָּן שִׁמְעוֹן בֶּן גַּמְלִיאֵל אוֹמֵר: אֵינוֹ צָרִיךְ.
Our Rabbanan have taught: One does not embark on a ship within 3 days before Shabbos. In what case? For a devar reshus. But for a devar mitzvah — shapir dami (it is perfectly muttar), and one settles with the boatman that he will rest. Rashbag says: even that condition is not necessary.
The halacha follows Rashbag according to the Rosh. But the Mechaber retains the convention as l'chatchilah.
Link with the surrounding simanim
| Siman | Subject | Link with רמ״ח |
|---|---|---|
| רמ״ד | Melacha done by a non-Jew | Conceptual framework of amirah l'akum |
| רמ״ז | Letters and objects sent | Heter to send things but not to travel oneself |
| רמ״ח | Traveling oneself within 3 days before Shabbos | — |
| רמ״ט | Meals on erev Shabbos | Worthy preparation for Shabbos |
The conceptual structure of the siman: the issur is not simply "to move on Shabbos" — every Yid moves on Shabbos within his techum. The issur is to put oneself intentionally into a situation where the journey will structurally overlap Shabbos. The Mechaber gives three "exits" from this issur: (1) mitzvah motivation, (2) kanah shevisah before Shabbos, (3) a short enough route to arrive before Shabbos.
Section 3 — First key concept
The 3 days rule — ג' ימים קודם השבת
What is the 3 days rule?
The rule: one does not embark on a ship (nor join a shayara) within 3 days before Shabbos. Practically: Wednesday, Thursday, Friday and Shabbos itself = assur (according to the Magen Avraham and most poskim). Sunday, Monday, Tuesday = muttar.
How are the "3 days" counted?
The Mishnah Berurah notes (ס״ק ה): according to the Magen Avraham and the majority of poskim, Wednesday is included in the issur. But the Gra cites Rishonim who count the 3 days including Shabbos itself, which would make Wednesday muttar.
| Position | Wednesday | Thursday | Friday |
|---|---|---|---|
| Magen Avraham + majority | Forbidden | Forbidden | Forbidden |
| Gra (Vilna Gaon) | Permitted | Forbidden | Forbidden |
L'maaseh: a Sefardi follows the Mechaber and the Mishnah Berurah, treating Wednesday as included in the issur. An Ashkenazi following the Gra in this particular point may be lenient on Wednesday, but most poskim — even Ashkenazi — keep Wednesday assur for a devar reshus. When in doubt, ask your Rav.
Section 4 — Second key concept
דבר מצוה vs דבר רשות
The basic distinction
| Type | Strict definition | Halacha |
|---|---|---|
| דבר מצוה | Aliyah, Torah, an affirmative mitzvah | Permitted even on erev Shabbos |
| דבר הרשות | Pure tourism, personal pleasure | Assur within the last 3 days |
The extension of Rabbeinu Tam
Tosafos (Shabbos 19a): any journey that is not pure sightseeing falls under devar mitzvah:
- Business travel (לסחורה)
- Visiting a friend or close relative (לראות פני חבירו)
- Aliyah, Torah learning, hachnasas orchim, etc.
The Rema codifies this extension in his hagahah: "כל מקום שאדם הולך לסחורה או לראות פני חבירו — חשוב הכל דבר מצוה". In practice, in the Ashkenazi minhag, almost every journey qualifies as a devar mitzvah; only pure tourism remains a devar reshus.
Section 5 — Third key concept
פוסק עמו שישבות — posek imo sheyishbos
What is posek imo sheyishbos?
פוסק עמו שישבות — an explicit agreement with the boatman that "he will stop on Shabbos", even if in actual fact the ship will not stop. The Yid is, on his side, formally not requesting that the ship sail on Shabbos.
The Yid traveling is not the cause of the Shabbos navigation. If the ship continues anyway, it is against his stipulated request — therefore no chilul Shabbos is attributed to him.
The machlokes Tanna Kamma / Rashbag
| Position | Is the convention necessary? |
|---|---|
| Tanna Kamma (Rabbi) | YES — even for a devar mitzvah, one must be posek imo |
| Rashbag — halacha | NO — for a devar mitzvah it is not necessary |
The Rosh paskens like Rashbag. But the Mechaber writes the language of Tanna Kamma (posek imo sheyishbos) — meaning that l'chatchilah one tries to be posek, even if b'dieved a missing convention does not invalidate a mitzvah journey.
L'maaseh: nowadays it is structurally impossible to be posek with the captain of a commercial cruise ship or with an airline pilot. The convention is impracticable with a commercial operator. So practically: either the journey is a devar mitzvah (which, under Rabbeinu Tam, covers most journeys) and one may travel even within 3 days; or it is pure tourism, and the 3-days rule applies strictly.
Section 6 — Why 3 days?
The three classical pirushim
The Rishonim give three different reasons for the 3-days rule. Each pirush sheds light on a different limit-case of the halacha. The Mechaber, in Seif Beis, explicitly adopts the first one — oneg Shabbos — but the others retain their force in marginal cases.
Pirush A — Rashi and the Rif: משום עונג שבת
Rashi and the Rif: during the first 3 days at sea, one is physically suffering — seasickness, fatigue, disorientation. There is no oneg Shabbos possible. The Chazal's rule preserves the oneg.
→ Consequence: on rivers, no seasickness → rule does not apply (Mechaber Seif Beis).
Pirush B — Yereim and Ramban: משום איסור תחומין
Yereim and Ramban: when the ship is moving less than 10 tefachim above the seabed, one is in the terrestrial techum. One may end up traveling beyond the 2000 amos of techum Shabbos. The rule guards against the issur of techumin.
→ Consequence: deep water (more than 10 tefachim) → no problem; shallow water → problem.
Pirush C — Riva and Mahari: משום סכנה (פיקוח נפש)
Riva and Mahari: in case of a storm or some other peril at sea, the Yid traveling will be forced to be mechalel Shabbos for pikuach nefesh. So that one should not voluntarily place oneself in that situation, one does not embark so close to Shabbos.
→ Consequence: when safety is essentially guaranteed (a modern airliner, a sturdy ocean liner) → this pirush weakens; when there is still real risk of pikuach nefesh at sea → it remains relevant.
The three pirushim coexist and are cumulative in the poskim. Each illuminates a different borderline case. To analyze a modern situation, one should run all three: is there a risk to oneg Shabbos? a risk of techumin? a risk of pikuach nefesh? When all three reasons fall away, the halacha is at its most lenient; when one or more remain alive, one must consider them seriously.
Section 7 — Seif א
The base rule: mitzvah, posek imo sheyishbos, and a short route
מֻתָּר לְהַפְלִיג בִּסְפִינָה אֲפִלּוּ בְּעֶרֶב שַׁבָּת אִם הוֹלֵךְ לִדְבַר מִצְוָה, וּפוֹסֵק עִמּוֹ שֶׁיִּשְׁבּוֹת. וְאִם אַחַר כָּךְ לֹא יִשְׁבּוֹת — אֵין בְּכָךְ כְּלוּם. אֲבָל לִדְבַר הָרְשׁוּת אֵין מַפְלִיגִין בִּסְפִינָה בְּפָחוֹת מִג' יָמִים קוֹדֶם הַשַּׁבָּת. הגה: אֲבָל קוֹדֶם שְׁלֹשָׁה יָמִים — שָׁרֵי, אֲפִלּוּ בִּסְפִינָה שֶׁמּוֹשְׁכִין אוֹתוֹ עַל יְדֵי בְּהֵמוֹת, אֲפִלּוּ אֵין בְּגֹבַהּ הַמַּיִם י' טְפָחִים [מהרי"ק שורש מ"ה], וַאֲפִלּוּ בְּמָקוֹם שֶׁיִּצְטָרֵךְ הַיִּשְׂרָאֵל לַעֲשׂוֹת אַחַר כָּךְ מְלָאכָה בְּשַׁבָּת לְהוֹלִיךְ הַסְּפִינָה [ריב"ש סי' קנ"ב]. וְאִם הוּא דֶּרֶךְ מוּעָט כְּמוֹ מִצּוֹר לְצִידוֹן, שֶׁאֵין בֵּינֵיהֶם כִּי אִם מַהֲלַךְ יוֹם אֶחָד — מֻתָּר לְהַפְלִיג בְּעֶרֶב שַׁבָּת בַּבֹּקֶר, מִפְּנֵי שֶׁאֶפְשָׁר שֶׁיַּגִּיעַ שָׁם קוֹדֶם הַשַּׁבָּת. וּמָקוֹם שֶׁנָּהֲגוּ שֶׁלֹּא לְהַפְלִיג בְּעֶרֶב שַׁבָּת כְּלָל, אֲפִלּוּ דֶּרֶךְ מוּעָט — אֵין מַפְלִיגִין.
It is muttar to embark on a ship even on erev Shabbos if one travels for a devar mitzvah, and one is posek imo sheyishbos. And if afterwards the boatman does not stop — there is no kashya at all. But for a devar reshus, one does not embark on a ship within 3 days before Shabbos. Hagahah of the Rema: But more than three days before Shabbos it is permitted — even on a ship pulled by animals, even where the water is not ten tefachim deep [Maharik, shoresh 45], and even where the Yisrael will afterwards need to perform a melachah on Shabbos to move the ship along [Rivash, siman 152]. The Mechaber continues: if the route is short — such as from Tzor to Tzidon, which is no more than a single day's journey — one may embark on erev Shabbos in the morning, since one can arrive before Shabbos. And in a place where the custom is not to embark on erev Shabbos at all, even for a short route — one does not embark.
What is this seif about?
Seif Alef sets out the governing rule of the entire siman. It contrasts two scenarios:
- A journey motivated by a mitzvah (דבר מצוה) — muttar even on erev Shabbos, under two conditions.
- A journey motivated by leisure or personal convenience (דבר הרשות) — assur within the 3 days preceding Shabbos.
The Rema immediately adds a third heter: if the distance is so short that one can actually arrive before Shabbos, one may embark even on erev Shabbos morning, regardless of the motivation.
The central halachic question
What happens when a Yid embarks on erev Shabbos onto a ship that will be sailing on Shabbos? Seemingly, he "causes" indirect chilul Shabbos (the ship is moving, the sailors are working, he himself is being transported). The Mechaber answers with a three-step mechanism: (1) the mitzvah justifies the departure, (2) the posek imo sheyishbos convention removes responsibility, (3) if the boatman does not keep his word, it is not on the Yid's account.
The three cumulative conditions of Seif Alef
To embark on erev Shabbos according to the Mechaber:
- Devar mitzvah — the journey must serve a mitzvah (aliyah, learning, a chasunah, pidyon shvuyim, etc. — and per the Rema, vastly expanded).
- Posek imo sheyishbos — explicit convention l'chatchilah with the boatman that he will rest on Shabbos.
- Ein b'chach klum — if the boatman, despite his promise, continues sailing on Shabbos, the traveler has nothing for which to reproach himself.
The Rema's door: a short route (דרך מועט)
דֶּרֶךְ מוּעָט = "a short way." When the entire trip can be completed before kabbalas Shabbos, the 3-days rule simply does not apply — the problematic situation (traveling on Shabbos itself) does not even arise. The Rema gives the classical example of Tzor to Tzidon (the ancient Lebanese coast): barely a day's journey, so one may embark on Friday morning and arrive before nightfall.
The table of opinions
| Position | Rule | Logic |
|---|---|---|
| Mechaber (stam) | Devar mitzvah + posek imo = permitted; devar reshus = assur within 3 days | The Yid is not the active cause of Shabbos navigation when there is a convention |
| Rema (hagahah) | Adds the derech mu'at heter (short route arriving before Shabbos) | If there is no Shabbos at sea at all, there is no kashya |
| Mishnah Berurah | Follows the Mechaber; codifies the Rashbag pesak that the convention is l'chatchilah | L'maaseh: even without a possible convention, a devar mitzvah may travel |
Pesak in practice
Practical synthesis of Seif Alef:
- Mitzvah journey + convention → muttar even on erev Shabbos.
- Leisure journey → assur within 3 days of Shabbos (Wednesday/Thursday/Friday per the majority).
- Short route arriving before Shabbos → muttar regardless of motivation.
- If the convention is not honored by the captain → no chiyuv for the traveler.
Practical cases of Seif Alef
Case A — Short ferry Marseille-Bastia (≈12h, Friday morning): a modern Tzor-Tzidon. If the arrival is certain before licht-bentchen, embarking on Friday morning is muttar — this is the derech mu'at situation of the Rema.
Case B — Travel to attend a chasunah (mitzvah) spilling over Shabbos: a classic devar mitzvah. There remains the question of the convention: with a modern airline pilot or captain, the posek imo sheyishbos requirement is impracticable. The majority position follows Rashbag (the convention is not indispensable).
Case C — Friday morning flight for a pure vacation: pure devar reshus. Forbidden by the 3-days rule, unless arrival is certain well before Shabbos (the derech mu'at case).
Points to remember (Seif Alef):
- The Mechaber distinguishes mitzvah from reshus, not by the mode of transport.
- The posek imo sheyishbos convention remains l'chatchilah even though the halacha follows Rashbag.
- The Rema's exception (a short route) is structural: no Shabbos at sea = no kashya.
Comprehension question: Why does the posek imo sheyishbos convention protect the traveler even when the ship in fact does not stop? Which general halachic principle underlies this idea?
Section 8 — Seif ב
Why 3 days? Salt sea vs river
הָא דְּאֵין מַפְלִיגִין בִּסְפִינָה בְּפָחוֹת מִשְּׁלֹשָׁה יָמִים קוֹדֶם הַשַּׁבָּת — הַטַּעַם מִשּׁוּם עוֹנֶג שַׁבָּת, שֶׁכָּל שְׁלֹשָׁה יָמִים הָרִאשׁוֹנִים יֵשׁ לָהֶם צַעַר וּבִלְבּוּל. וְדַוְקָא לְמַפְלִיגִים בְּמַיִם הַמְּלוּחִים. אֲבָל בִּנְהָרוֹת אֵין שׁוּם צַעַר לְמַפְלִיגִים בָּהֶם — וּלְפִיכָךְ מֻתָּר לְהַפְלִיג בָּהֶם אֲפִלּוּ בְּעֶרֶב שַׁבָּת, וְהוּא שֶׁלֹּא יְהֵא יָדוּעַ לָנוּ שֶׁאֵין בְּעָמְקָם עֲשָׂרָה טְפָחִים. אֲבָל בְּמָקוֹם שֶׁיָּדוּעַ לָנוּ שֶׁמִּקַּרְקַע הַסְּפִינָה לְקַרְקַע הַנָּהָר פָּחוֹת מֵעֲשָׂרָה טְפָחִים — אָסוּר (לָצֵאת חוּץ לַתְּחוּם) מִשּׁוּם אִסּוּר תְּחוּמִין. הגה: וְכֵן בִּסְפִינָה שֶׁיִּצְטָרֵךְ הַיִּשְׂרָאֵל לָבֹא לִידֵי מְלָאכָה בְּשַׁבָּת — אָסוּר לִיכָּנֵס בָּהּ שְׁלֹשָׁה יָמִים קוֹדֶם הַשַּׁבָּת, אֲפִלּוּ הֵם נְהָרוֹת הַנּוֹבְעִים וְהוּא לְמַעְלָה מֵעֲשָׂרָה (ריב"ש סי' קנ"ב מהרי"ק). אֲבָל אֵין אִסּוּר בְּמַה שֶּׁהַבְּהֵמוֹת מוֹשְׁכוֹת הַסְּפִינָה בִּשְׂפַת הַנָּהָר, וְלֹא דָּמֵי לַהֲלִיכָה בְּקָרוֹן שֶׁאָסוּר.
The reason for the rule that one does not embark within 3 days before Shabbos is oneg Shabbos: during the first 3 days at sea one suffers tza'ar u-bilbul (seasickness). This applies only to those sailing on salt water. On rivers there is no such tza'ar for those sailing on them — therefore one may embark even on erev Shabbos, provided it is not known to us that their depth is less than ten tefachim. But in a place where we know that there are less than ten tefachim between the bottom of the ship and the riverbed — it is assur (to go beyond the techum), because of issur techumin. Hagahah of the Rema: And likewise, on a ship where the Yisrael will come to need to do a melachah on Shabbos, it is assur to board it within the three days before Shabbos — even if these are flowing rivers and the ship is more than ten tefachim above the riverbed [Rivash siman 152, Maharik]. But there is no issur in the animals pulling the ship along the riverbank — and it is not comparable to traveling in a wagon, which is assur.
What is this seif about?
Seif Beis answers a natural question raised by Seif Alef: why exactly 3 days? The Mechaber explains: during the first 3 days of a sea voyage, the body suffers a tza'ar u-bilbul — seasickness, disorientation, vomiting, loss of appetite. But Shabbos requires oneg (pleasure, dignified meals, rest). Embarking too close to Shabbos = spending Shabbos sick = no oneg possible.
From this oneg-based explanation, the Mechaber draws a radical consequence: the rule applies only to salt sea. On a river (fresh water, calm navigation, no seasickness) there is no tza'ar — and therefore no 3-days rule.
The halachic question
The point of analysis: is the 3-days rule universal (any sea voyage) or conditional (only when there is a concrete risk to oneg Shabbos)? If conditional, then any comfortable voyage (a calm river, a modern stabilized cruise liner) could fall outside the perimeter.
The key concept: oneg Shabbos as an operational criterion
עוֹנֶג שַׁבָּת = "the pleasure of Shabbos." Affirmative obligation (passuk וקראת לשבת עונג, Yeshayahu 58:13) to honor Shabbos with meals, rest, and dignified clothing. Any situation that structurally precludes oneg is suspect in the eyes of Chazal — hence the 3-days rule for sea voyages, where the first days are physically distressing.
The salt-sea / river distinction
| Type of water | Tza'ar u-bilbul? | 3-days rule? | Embark on erev Shabbos? |
|---|---|---|---|
| Salt sea (ים המלוח) | Yes | Applies | Assur (unless mitzvah) |
| River (נהר) | No | Does not apply | Muttar |
| Calm lake | Effectively no | Does not apply | Muttar (analogous to a river) |
Pesak in practice
Synthesis of Seif Beis:
- The 3-days rule is founded on oneg Shabbos — not on an abstract notion of "displacement".
- Fresh water (river, canal, lake) → rule inoperative.
- Salt sea → rule fully applicable.
- If one will have no melacha to do on board and the ship is operated by non-Jews, there remain the other considerations (techumin, maris ayin) addressed in the meforshim.
Practical cases of Seif Beis
Case A — Ferry on Lac Léman on Friday evening: fresh water, a one-hour trip, no tza'ar. The 3-days rule of Seif Beis does not engage. There remains the question of when the trip finishes: if one arrives before Shabbos, the case is straightforward.
Case B — 7-day transatlantic cruise: salt sea — the textbook case of Seif Beis. The first days on the open sea carry potential tza'ar. The 3-days rule is fully applicable, unless it is a devar mitzvah.
Case C — A modern ultra-stabilized liner with calm seas forecast: an open question among the Acharonim. Some preserve the 3-days rule for salt sea per se; others are lenient when comfort is guaranteed. Follow your Rav.
Case D — A river cruise on the Rhine or the Danube (fresh water): according to Seif Beis, the 3-days rule does not apply. One may embark closer to Shabbos — only the technical questions remain (preparing Shabbos, melachos on board).
Points to remember (Seif Beis):
- The Mechaber gives the ta'am: oneg Shabbos. Understanding the ta'am allows the rule to be modulated in borderline cases.
- The mayim ha-meluchim / neharos distinction is structural — modern practice depends entirely on it.
- When the rationale falls away (a river, secured comfort, a short duration), the rule itself recedes.
Comprehension question: The Mechaber bases the 3-days rule on oneg Shabbos. If someone proves he will have no seasickness (medication, a stabilized vessel), may one relax the rule? What are the arguments for and against?
Section 9 — Seif ג
Kanah shevisah: boarding the ship before Shabbos
הֵיכָא דְּמֻתָּר לְהַפְלִיג מֵעֶרֶב שַׁבָּת, אִם נִכְנַס בַּסְּפִינָה מֵעֶרֶב שַׁבָּת וְקָנָה בָהּ שְׁבִיתָה — אַף עַל פִּי שֶׁמַּפְלֶגֶת בְּשַׁבָּת מֻתָּר, וְהוּא שֶׁלֹּא יֵצֵא מֵהַסְּפִינָה מֵעֵת שֶׁקָּנָה שְׁבִיתָה. הגה: וְיֵשׁ אוֹמְרִים דַּאֲפִלּוּ יָצָא מִן הַסְּפִינָה שָׁרֵי, דְּמֵאַחַר שֶׁקָּנָה בָהּ שְׁבִיתָה מֵעֶרֶב שַׁבָּת — מֻתָּר אַחַר כָּךְ לִיכָּנֵס בָּהּ בְּשַׁבָּת וּלְהַפְלִיג. וְיֵשׁ אוֹמְרִים שֶׁעוֹשִׂין קִדּוּשׁ בַּסְּפִינָה וְאַחַר כָּךְ חוֹזְרִים לְבֵיתָם וְלָנִים שָׁם, וּלְמָחָר חוֹזְרִין לַסְּפִינָה וּמַפְלִיגִין. כֵּן נָהֲגוּ בִּקְצָת מְקוֹמוֹת וְאֵין לִמְחוֹת (ר"ן פ"ק דשבת וריב"ש סי' י"ז קכ"א קכ"ב), וְעַיֵּן לְקַמָּן סִי' של"ט ות"ד.
Wherever it is permitted to embark on erev Shabbos, if one entered the ship on erev Shabbos and was kanah shevisah in it, even though the ship sets sail on Shabbos itself — it is muttar, provided he did not leave the ship from the moment he was kanah shevisah. Hagahah of the Rema: Some say that even if he left the ship it is permitted: since he was kanah shevisah in it on erev Shabbos, he may afterwards re-enter it on Shabbos and set sail. And some say that one makes Kiddush on the ship, then returns home and sleeps there, and the next day returns to the ship and sets sail; such is the minhag in some places, and one should not protest [Ran, first perek of Shabbos; Rivash simanim 17, 121, 122]. And see further siman 339 and siman 404.
What is this seif about?
Seif Gimel addresses a hybrid case: a situation where embarking is already permitted (a mitzvah, or a short route, or a river), but where the ship only physically departs on Shabbos itself. May one still come on board before Shabbos? The Mechaber answers yes, provided one has been kanah shevisah (קנה שביתה) before kabbalas Shabbos.
The halachic question
The point of analysis: Shabbos fixes a person at a place (the 2000 amos of techum Shabbos). If at the entry of Shabbos the traveler is already on board, is his techum that of the ship (which will move) or that of the place where he was at twilight? The Mechaber resolves it: by "being kanah shevisah" on the ship before nightfall, the traveler makes the ship his shabbosdike anchor point — and may continue to be carried with it.
The key concept: kanah shevisah
קָנָה שְׁבִיתָה = "he has acquired his shevisah." A juridico-halachic act by which a traveler fixes his techum Shabbos at a specific place (often by a meaningful act: depositing his belongings, making Kiddush, an explicit declaration "here I am being kove'a Shabbos"). By entering the ship before nightfall with the intent to remain there for Shabbos, the traveler attaches his techum to the ship itself — which becomes his "mobile residence."
The three conditions of Seif Gimel
To benefit from Seif Gimel:
- A case where embarking is already permitted — mitzvah, derech mu'at, river, etc.
- Boarding the ship before kabbalas Shabbos — physically on board before nightfall.
- Kanah shevisah ba-sefina — a significant act (Kiddush on board, a clear deposit of belongings, intent to remain).
The table of opinions
| Position | Rule | Logic |
|---|---|---|
| Mechaber (stam) | Permitted if kanah shevisah and one does not disembark | The techum is fixed on the ship; the Yid travels with his own techum |
| Rema (Ashkenazi practice) | Even more lenient — the minhag tolerates Kiddush on the ship and sleeping ashore, returning to embark on Shabbos | "They have on whom to rely" — yesh la-hem al mi lismoch |
| Mishnah Berurah | Follows the Mechaber as the rule, accepts the Rema for the minhag | For an Ashkenazi the practice is broader; for a Sefardi one keeps to the strict reading |
Pesak in practice
Synthesis of Seif Gimel:
- Seif Gimel extends the heter of Seif Alef: the ship does not need to leave before Shabbos — only the traveler needs to be on board.
- The act of kanah shevisah is essential — being there by chance is not enough.
- According to the strict Mechaber, the traveler should not disembark on Shabbos (otherwise he leaves his techum).
- The Rema is more lenient: one may go down and come back, and the minhag tolerates even sleeping ashore.
Practical cases of Seif Gimel
Case A — Boarding on Friday evening for sailing Saturday morning: one comes on board, makes Kiddush on deck, eats the Friday night seudah. The ship weighs anchor Saturday at 6 a.m. Muttar per Seif Gimel — the traveler was kanah shevisah on the ship.
Case B — Plane on the tarmac Friday evening, takeoff after kabbalas Shabbos (modern application): an analogous situation. The passenger is on board before Shabbos, the plane only takes off after nightfall. If the journey falls within the heterim of Seif Alef (a mitzvah, etc.) and one has been kanah shevisah on the aircraft, contemporary poskim apply the principle. Always ask one's Rav for the actual case.
Case C — Tourist cruise: boarding Friday 5 p.m., sailing Saturday 9 a.m.: problematic. Even if one boards before Shabbos, the motivation (leisure) is already outside the heterim of Seif Alef. Seif Gimel only applies "היכא דמותר להפליג" — where embarking is already permitted.
Points to remember (Seif Gimel):
- Seif Gimel presupposes that Seif Alef permits the journey. It does not create a fresh heter.
- Kanah shevisah demands a meaningful act, not just incidental presence.
- The ship becomes an extension of one's Shabbos residence.
Comprehension question: Why does the Mechaber specify "היכא דמותר להפליג" ("where embarking is already permitted") at the start of Seif Gimel? What would change if this clause were missing?
Section 10 — Seif ד
The shayara (caravan) in the desert and aliyah l'Eretz Yisrael
הַיּוֹצְאִים בְּשַׁיָּרָא בַּמִּדְבָּר וְהַכֹּל יוֹדְעִים שֶׁהֵם צְרִיכִים לְחַלֵּל שַׁבָּת, כִּי מִפְּנֵי הַסַּכָּנָה לֹא יוּכְלוּ לְעַכֵּב בַּמִּדְבָּר בְּשַׁבָּת לְבַדָּם — ג' יָמִים קוֹדֶם שַׁבָּת אֲסוּרִים לָצֵאת, וּבְיוֹם רִאשׁוֹן וּבַשֵּׁנִי וּבַשְּׁלִישִׁי מֻתָּר לָצֵאת. וְאִם אַחַר כָּךְ יֶאֱרַע לוֹ סַכָּנָה וְיִצְטָרֵךְ לְחַלֵּל שַׁבָּת מִפְּנֵי פִּקּוּחַ נֶפֶשׁ — מֻתָּר, וְאֵין כָּאן חִלּוּל. וְהָעוֹלֶה לְאֶרֶץ יִשְׂרָאֵל, אִם נִזְדַּמְּנָה לוֹ שַׁיָּרָא אֲפִלּוּ בְּעֶרֶב שַׁבָּת — כֵּיוָן דִּדְבַר מִצְוָה הִיא יָכוֹל לִפְרֹשׁ, וּפוֹסֵק עִמָּהֶם לִשְׁבּוֹת. וְאִם אַחַר שֶׁיִּהְיוּ בַּמִּדְבָּר לֹא יִרְצוּ לִשְׁבּוֹת עִמּוֹ — יָכוֹל לָלֶכֶת עִמָּהֶם חוּץ לַתְּחוּם מִפְּנֵי פִּקּוּחַ נֶפֶשׁ. וְאִם נִכְנַס לְעִיר אַחַת בְּשַׁבָּת — מְהַלֵּךְ אֶת כֻּלָּהּ, וַאֲפִלּוּ הִנִּיחוּהוּ מִחוּץ לָעִיר וְרוֹצֶה לִיכָּנֵס לָעִיר מֻתָּר, דְּכֵיוָן דְּלִדְבַר מִצְוָה נְפַק — יֵשׁ לוֹ אַלְפַּיִם אַמָּה לְכָל רוּחַ.
For those who set out with a shayara into the desert — where everyone knows they will be forced to be mechalel Shabbos, for because of the sakanah they will not be able to stay behind alone in the desert on Shabbos — within 3 days before Shabbos it is assur to depart; but on Sunday, Monday, and Tuesday (days 1, 2, 3) it is muttar to depart. And if afterwards a sakanah befalls him and he must be mechalel Shabbos because of pikuach nefesh — it is muttar, and there is no chilul here. And one who is doing aliyah l'Eretz Yisrael, if a shayara presents itself even on erev Shabbos — since it is a devar mitzvah, he may set out; and he stipulates with them that they will rest on Shabbos. And if, once they are in the desert, they do not want to rest with him — he may go with them beyond the techum, because of pikuach nefesh. And if he enters a city on Shabbos — he may walk through all of it; and even if they left him outside the city and he wants to enter it — it is muttar: since he set out for a devar mitzvah, he has 2000 amos in every direction.
What is this seif about?
Seif Daled extends the 3-days rule from sea travel to terrestrial caravans (שיירא) crossing the desert. The same logic: if one knows that the caravan will be mechalel Shabbos (to flee bandits, to survive the heat, to reach an oasis), one does not join it within the 3 days before — unless it is a clearly defined mitzvah, the paradigmatic example being aliyah l'Eretz Yisrael.
The halachic question
The point of analysis: embarking in a vehicle that certainly will operate on Shabbos — is it permitted? And does aliyah — a major collective mitzvah — justify departing even on erev Shabbos, when one knows one will be forced to continue? The Mechaber rules: the 3-days rule extends to the caravan, but aliyah breaks through the rule (as does any clear mitzvah).
The two parts of Seif Daled
| Case | Halacha | Reasoning |
|---|---|---|
| Non-mitzvah shayara, within 3 days of Shabbos | Assur | A certain coming chilul Shabbos |
| Non-mitzvah shayara, Sunday through Tuesday | Muttar | Far enough from Shabbos that the issur does not apply |
| Aliyah l'Eretz Yisrael | Muttar even on erev Shabbos | A clearly defined devar mitzvah |
The key concept: shayara — the land version
שַׁיָּרָא = caravan, convoy. In the era of the Shulchan Aruch, crossing a desert (the Sinai, the Negev, the Sahara) required traveling in a group with pack animals. The shayara did not stop on Shabbos (questions of safety, of water, of grazing). A Yid joining it knew in advance that he would, at a minimum, have to walk on Shabbos or have his beasts carry. Seif Daled takes up the logic of Seif Alef and applies it to the land.
Aliyah l'Eretz Yisrael as the paradigm mitzvah
Why aliyah breaks through the rule: ascending to Eretz Yisrael is treated by Chazal as so fundamental a mitzvah that it overrides the 3-days rule. The Mechaber writes explicitly "כיון דדבר מצוה היא" — since it is a devar mitzvah. This is the paradigm-case that serves as the model for all other mitzvos that justify a late departure.
Pesak in practice
Synthesis of Seif Daled:
- The 3-days rule extends to caravans / land vehicles that will be operating on Shabbos.
- Sunday-Tuesday: muttar for any motivation (including leisure) — one is far enough from Shabbos.
- Wednesday-Friday: assur, except for a mitzvah.
- Aliyah: the paradigm mitzvah, muttar whatever the day.
Practical cases of Seif Daled
Case A — Non-Jewish overnight bus Thursday evening, arrival Friday morning: arrival before Shabbos → outside the rule. Like the short ferry of Seif Alef.
Case B — Caravan / convoy on Thursday for a 5-day crossing: assur, unless a mitzvah. The textbook Seif Daled case: one knows the convoy will run on Shabbos, one is within the 3 days.
Case C — Flight Friday 11 a.m. for aliyah, landing in Tel Aviv 5 p.m.: muttar without question. A direct application of Seif Daled: aliyah l'Eretz Yisrael = paradigmatic devar mitzvah.
Case D — Overnight train Thursday for a Torah conference Friday morning: arrival before Shabbos and mitzvah (learning). Two heter-titles combine — muttar without difficulty.
Case E — Thursday flight for tourist sightseeing in Eretz Yisrael (leisure): an ambiguous case. The fact that the destination is Eretz Yisrael does not by itself change anything if the motive is purely touristic. But if the trip also includes visiting holy places, it can tip into a mitzvah. Ask your Rav.
Points to remember (Seif Daled):
- The 3-days rule is not specific to ships — it applies to any travel that spills into Shabbos.
- Aliyah is the paradigm example of devar mitzvah that pierces the rule.
- The day-counting is the same as for ships (Seif Alef).
- For the short version / arriving before Shabbos: direct application of the Rema.
Comprehension question: Why does the Mechaber take aliyah l'Eretz Yisrael as the model mitzvah that pierces the rule? Do other mitzvos (a chasunah, a milah of a close relative, pidyon shvuyim) have the same status?
Section 11
The position of the Rema — what changes for an Ashkenazi
The Rema (Rav Moshe Isserles) adds four crucial elements to the Mechaber's pesak:
Element 1 — Animal-drawn vessels before the 3 days
The Rema permits embarking before the 3 days on a vessel pulled by animals (e.g. a tow-boat), even in shallow water, and even when the Yid himself will be physically helping on Shabbos.
Element 2 — Rivers within the 3 days
On rivers: no kashya for the 3 days, provided the Yid himself has no melacha to perform.
Element 3 — The minhag of Kiddush on the ship
Making Kiddush on the ship, sleeping ashore, and returning to set sail on Shabbos. The Rema writes: "it is not to be opposed, for they have on whom to rely."
Element 4 — Rabbeinu Tam's extension (the most important)
Practical consequence: in the majority Ashkenazi practice, almost any journey is a devar mitzvah. The 3-days rule applies strictly only to pure tourism.
Mechaber vs Rema table
| Case | Mechaber (strict Sefardi) | Rema (Ashkenazi practice) |
|---|---|---|
| Business travel within the 3 days | Assur | Muttar (Rabbeinu Tam) |
| Visiting a friend | Assur | Muttar |
| Pure tourism | Assur | Assur |
| Animal-drawn vessel before the 3 days | Muttar with conditions | Muttar broadly |
Note for the Mishnah Berurah: the Mishnah Berurah, while following the Mechaber as the formal rule, brings the Rema for Ashkenazi practice and emphasizes Rabbeinu Tam's broad understanding of devar mitzvah. In practice, most contemporary poskim — both Sefardi and Ashkenazi — adopt a moderate version of Rabbeinu Tam's extension for any journey with real purpose (business, family, simcha, Torah).
Section 12
Modern practical cases
Case 1 — Long-haul flight Friday into Shabbos
Case: Paris → New York flight Friday 2 p.m., landing NY 5 p.m. local (but Shabbos in Paris at 6 p.m., so the aircraft is flying during Shabbos in Paris time).
Conduct: muttar if it is a devar mitzvah. For halacha l'maaseh, ask your Rav, especially if the flight entails chilul Shabbos issues on board.
Conduct: muttar if it is a devar mitzvah. For halacha l'maaseh, ask your Rav, especially if the flight entails chilul Shabbos issues on board.
Case 2 — Mediterranean cruise Thursday-Sunday
Case: a 4-day cruise (Thursday → Sunday), boarding Thursday evening.
Conduct: problematic. A tourist cruise falls squarely in the case the siman is meant to prohibit. Embark at least 3 days before Shabbos (Tuesday) or ask a Rav.
Conduct: problematic. A tourist cruise falls squarely in the case the siman is meant to prohibit. Embark at least 3 days before Shabbos (Tuesday) or ask a Rav.
Case 3 — Overnight train Thursday evening → Friday morning
Case: overnight train Thursday 10 p.m. → Friday 8 a.m.
Conduct: muttar without difficulty. An overnight train is not within the perimeter of Siman רמ״ח (one arrives before Shabbos).
Conduct: muttar without difficulty. An overnight train is not within the perimeter of Siman רמ״ח (one arrives before Shabbos).
Case 4 — Business travel abroad with the trip overlapping Shabbos
Case: a businessman traveling to see a client, flight Friday 4 p.m., return Sunday.
Conduct: per the Rema, muttar (parnassah = mitzvah). Per the strict Mechaber, more problematic.
Conduct: per the Rema, muttar (parnassah = mitzvah). Per the strict Mechaber, more problematic.
Case 5 — Aliyah l'Eretz Yisrael on a Friday
Case: aliyah, flight Friday 11 a.m., landing in Tel Aviv 5 p.m.
Conduct: muttar without any doubt. The textbook case of the Mechaber in Seif Daled.
Conduct: muttar without any doubt. The textbook case of the Mechaber in Seif Daled.
Section 13
Practical synthesis of the siman
The 4 teachings of Siman רמ״ח:
- Base rule: do not embark within 3 days before Shabbos for a leisure journey.
- Mitzvah exception: muttar even on erev Shabbos with the convention (the Rema vastly extends "mitzvah").
- Short distance: if one can arrive before Shabbos → muttar.
- Kanah shevisah: entering the ship before Shabbos with a meaningful act → muttar afterwards.
Practical decision table
| Situation | Conduct |
|---|---|
| Leisure / tourism within the 3 days | Assur (Mechaber and Rema) |
| Business / family travel within the 3 days | Per the Rema: muttar (Rabbeinu Tam). Strict Sefardi: assur. Follow your minhag. |
| Aliyah l'Eretz Yisrael any day | Muttar |
| Train, short flight arriving before Shabbos | Muttar (modern Tzor-Tzidon) |
| Long-haul flight overlapping Shabbos — mitzvah | Per the Rema muttar; strict Mechaber problematic |
| Cruise overlapping Shabbos — leisure | Very problematic — ask a Rav |
| Travel into a zone of danger | Pikuach nefesh overrides |
The 5 practical pillars of Siman רמ״ח
- Distinguish mitzvah from reshus — per the Rema, almost every journey is a mitzvah, except pure tourism.
- Respect the 3-days rule for journeys clearly classified as non-mitzvah.
- Honor Shabbos on board: Kiddush, davening, dignified seudos.
- Do not voluntarily place oneself in a chilul-Shabbos situation (other than pikuach nefesh).
- Ask your Rav for the borderline cases.
Section 14
Comprehension questions
Test your understanding:
- What is the base rule of Siman רמ״ח? From which day on is embarking assur?
- What are the 3 classical pirushim for the 3-days rule?
- What is פוסק עמו שישבות? What is the machlokes of Tanna Kamma vs Rashbag?
- The difference between דבר מצוה and דבר רשות according to Rabbeinu Tam?
- Why does the Mechaber permit embarking on erev Shabbos from Tzor to Tzidon?
- What is קנה שביתה בספינה?
- What does the Mechaber say in Seif Daled about aliyah?
- For a leisure cruise boarding on Thursday: muttar or assur?
- For a business trip with a long-haul flight on Friday: Mechaber vs Rema?
- What is the alternative position of the Gra on Wednesday?
To go further
If you want to delve deeper into this siman:
- 📖 Level 2 — Lamdan: for pilpul, the 3 pirushim treated in depth, the shitos of the Rishonim, fundamental chakiros, and the Acharonim's nuances
- ✨ Level 3 — Synthesis: for rapid review with mnemonics (G-M-S) and decision trees
- 🎓 Level 4 — Daat HaRav: the shitah of the Admur HaZaken (Shulchan Aruch HaRav siman רמ״ח)