Siman קכ״א — Kashering vessels bought from a non-Jew (הכשר כלים)
Cold, hot, fire — every use has its own kashering
יורה דעה · סימן קכ״א
סדר הכשר כלים הנקנים מן העובד כוכבים
🌱 Foundations level · מתחילים
✦ ❖ ✦
A first approach to Siman 121: the seven seifim of the Mehaber and the glosses of the Rama, Hebrew text with a fluent English translation. A vessel a non-Jew has already used has absorbed a forbidden taste; to make it usable, that taste must be driven back out. And the whole siman rests on a single sentence: כדרך שנשתמש בהן העובד כוכבים כך הוא הכשרן, kashering follows use. What remains is to learn what הדחה, הגעלה, ליבון and נעיצה actually mean.
Subject: Kashering vessels acquired from a non-Jew — הדחה, הגעלה, ליבון, נעיצה Source: שולחן ערוך יורה דעה סימן קכ״א
Compiled by: הרב יוסף חיים סממה DAAT · daattorah.com
📑 Plan of study
1.The Mehaber’s text: the 7 seifim, by thematic groups
2.Background: the mishna in Avoda Zara and the Rambam’s ladder
3.The key concepts: הדחה, הגעלה, ליבון, בן יומו, כבולעו כך פולטו, גומות…
4.The three rungs: the use → kashering table
5.The Taz and the Shach: two key entries
6.The Rama’s gloss (הגה): the line of received practice
7.Practical cases today: a rented kitchen, the oven, the frying pan, the knife
8.Summary and comprehension questions
1. The Mehaber’s text — the 7 seifim
Siman 120 required that a vessel bought from a non-Jew be immersed; Siman 121 requires that, once it has already been used, it be kashered. These are two distinct operations, and they even have an order. The Mehaber (Rabbi Yosef Karo) handles the matter in only seven seifim, yet those seven set out the entire system: first the governing rule and its two first applications, cold and hot (seifim 1-3); then the cases where הגעלה does not suffice and fire is needed (seifim 4-6); and finally the most debated case of all, the knife (seif 7). The Rama (Rabbi Moshe Isserles) adds his glosses (הגה), and here they have a particular colour: they report above all what is actually done — והכי נוהגין, ואין לשנות.
Group A — The governing rule, cold use and hot use (seifim 1-3)
Seif 1 — כדרך תשמישו כך הכשרו: a vessel used with cold
הלוקח כלים ישנים מן העובד כוכבים כדרך שנשתמש בהן העובד כוכבים כך הוא הכשרן לפיכך הלוקח כלי תשמיש ישנים שנשתמש בהם בצונן כגון כוסות וצלוחיות וכיוצא בהן מדיחן וצריך לשפשפן היטב במים בשעת הדחה כדי להסיר ולמרק האיסור שעל גביהן ואחר כך שוטפן במים ומטבילן והם מותרים: הגה יש מקומות שנהגו היתר לשום יין בכלים שנסריהם מדובקים בחלב משום שטבע היין לברוח מן החלב והחלב נקרש ועומד בעצמו ואינו נוגע כלל ביין (ריב״ש סימן קמ״ט):
One who buys used vessels from a non-Jew: the manner in which the non-Jew used them is the manner of their kashering. Therefore one who buys used utensils that were used with cold — cups, small flasks and the like — rinses them (מדיחן), and he must scrub them well in water at the time of rinsing, so as to remove and scour off the forbidden matter on their surface; afterwards he washes them in water and immerses them, and they are permitted. Rama’s gloss: there are places where the custom is to permit putting wine into casks whose staves are sealed with fat, because the nature of wine is to flee from the fat: the fat congeals and stands on its own and does not touch the wine at all.
The sentence that governs the whole siman:כדרך שנשתמש בהן העובד כוכבים כך הוא הכשרן. We do not ask what the vessel is made of, nor what it held: we ask by what degree of heat the taste entered. This is the principle of כבולעו כך פולטו — as it absorbed, so it expels. Three uses, three procedures: cold → rinsing, hot → הגעלה, fire → ליבון.
An easily missed word: the seif does not merely say “rinse”; it says וְצָרִיךְ לְשַׁפְשְׁפָן הֵיטֵב — and he must scrub them well. With cold, nothing entered the wall: the forbidden matter is on the vessel, not in it. Hence it is enough to remove it — but it must really be removed.
Seif 2 — Hot use: הגעלה, and its order relative to immersion
לקח מהם כלים שנשתמש בהם בחמין בין שהם של מתכת או של עץ או אבן מגעילן ואחר כך מטבילן אם הם של מתכת והם מותרים ואם הטבילן ואחר כך הגעילן מותרים ויש אומרים שצריך לחזור ולהטבילן: הגה דין כלי עצם עיין בהלכות פסח סי׳ תנ״א. אין להגעיל שום כלי כל זמן שהוא בן יומו (טור) ואין להשתמש במי הגעלה (ארוך) כל מקום שצריך הגעלה לא מהני אם קלפו לכלי בכלי אומנות (ת״ה סי׳ ק״ל ובמרדכי והגהת ש״ד) ועיין לעיל סימן ק״ח דין מרדה של איסור:
If he took from them vessels that were used with hot — whether of metal, of wood or of stone — he scalds them (מגעילן), and afterwards immerses them if they are of metal, and they are permitted. And if he immersed them and afterwards scalded them, they are permitted; some say that he must immerse them again. Rama’s gloss: for the law of bone vessels, see Hilkhot Pesach. No vessel is to be scalded while it is בן יומו; the water of the הגעלה may not be used; and wherever הגעלה is required, it does not help to shave the vessel down with a craftsman’s tool.
The order of the two operations. Kashering (הכשר) comes before immersion (טבילה): a vessel still charged with forbidden taste is not brought into the sanctity of Israel. Yet the Mehaber allows the reverse order after the fact — מותרים — while the וי״א requires a second immersion. Remember: first הכשר, then טבילה.
בן יומו — a vessel “of the day”, one used with the forbidden food within the past twenty-four hours. Its absorbed taste is still enhancing; after that, it is deemed spoiled (נותן טעם לפגם — the whole subject of Siman 122). From this the Rama draws a practical safeguard: a vessel that is ben yomo is not kashered, for the taste it expels would itself taint the water of the vat.
Seif 3 — The cross-reference to Hilkhot Pesach
דיני הגעלה וליבון הלא הם כתובים בהלכות פסח:
The laws of הגעלה and ליבון — they are written in Hilkhot Pesach.
A one-line seif, and a decisive one. The Mehaber refuses to duplicate the material: the procedure of kashering is set out once and for all in Orach Chaim, in the laws of chametz (שו״ע או״ח סימן תנ״א). Yoreh De‘ah keeps only what is its own — which procedure for which vessel. That is also why the following seifim never discuss water temperature or the size of the vat: all of that is elsewhere.
Group B — When הגעלה does not suffice: ליבון (seifim 4-6)
Seif 4 — The frying pan: why boiling water is not enough
מחבת שמטגנים בה אע״פ שלענין חמץ בפסח די לה בהגעלה לענין שאר איסורים צריכה ליבון:
A frying pan (מחבת) in which one fries: although, as regards chametz on Pesach, הגעלה suffices for it, as regards other prohibitions it requires ליבון.
The same vessel, two regimes. Why should the pan be easier to kasher for Pesach than for non-kosher meat? Because chametz, before Pesach, was permitted: the vessel absorbed something permitted, which only became forbidden afterwards. The Taz says it in four words: כיון דהיתרא קא בלע. A prohibition absorbed as a prohibition is treated more strictly.
כיון דהיתרא קא בלע
— ט״ז יו״ד קכ״א ס״ק ג
And why fire rather than water? Because frying is done without water: the taste enters the wall through direct contact between the fat and the heated metal. As it absorbed, so it expels: what entered through fire will leave only through fire.
Seif 5 — הגעלה was done where ליבון was required
אם הגעיל כלי הצריך ליבון אסור להשתמש בו בחמין אפילו שלא על ידי האש: הגה אבל מותר להשתמש בו צונן אפילו לכתחלה ע״י הדחה ושפשוף היטב וכ״ש בכלי שצריך הגעלה ודוקא בדרך עראי כגון שהוא בבית העובד כוכבים או בדיעבד אבל אם רוצה להשתמש בו בקבע יש מחמירים ואומרים דאפילו להשתמש בו צונן צריך הגעלה או ליבון גזרה שמא ישתמש בו חמין (מרדכי ורוקח) והכי נוהגין ואפילו כלים שתשמישן בצונן אם יש לחוש שחממו בו יין כגון כלי כסף נוהגין להגעיל ואין לשנות (ארוך בשם ראבי״ה) ואפילו תיבות ושלחנות הנקחים מן העובדי כוכבים נוהגין להגעיל שמא נשפכו עליהם חמין ודוקא לכתחלה אבל בדיעבד אין לחוש לכל זה (שם) וכלי חרס שנשתמשו בו בצונן מאחר דאי אפשר בהגעלה מקרי דיעבד וסגי ליה במריקה ושטיפה היטב (שם) ומותר ליתן בו אח״כ אפילו דברים חריפים כחומץ וכיוצא בו וכ״ש דברים קשים כתבלין וכיוצא בהן וע״ל סימן צ״א:
If one performed הגעלה on a vessel that required ליבון, it is forbidden to use it with hot food, even not directly on the fire. Rama’s gloss: but it is permitted to use it cold, even at the outset, by rinsing and thorough scrubbing — and all the more so for a vessel that required only הגעלה. That, however, holds only for occasional use, for instance when one is in the non-Jew’s house, or after the fact; for permanent use, some are stringent and require הגעלה or ליבון even for cold, lest one come to use it with hot food — and such is the practice. And even vessels used only with cold, where there is reason to suspect that wine was warmed in them — such as silver vessels — the practice is to perform הגעלה, and one should not deviate. And even chests and tables bought from non-Jews are customarily scalded, lest hot food was spilled on them — at the outset only, for after the fact there is nothing to be concerned about in all this. And an earthenware vessel used only with cold: since הגעלה is impossible, it is deemed a case of “after the fact”, and thorough scouring and rinsing suffice for it. It is then permitted to place in it even sharp foods such as vinegar, and all the more so hard foods such as spices.
An insufficient kashering is not half a kashering. The Mehaber’s wording is severe: הגעלה performed in place of ליבון does not count. Nothing has been “gained” — the vessel remains forbidden for hot use, even for heat in a secondary vessel. The Taz notes that this severity applies to the Mehaber’s words, not to the Rama’s gloss that follows.
The richest gloss of the siman. Here the Rama introduces a distinction that governs all practice: עראי / קבע — occasional versus permanent use. What is tolerated for a single glass drunk in passing is not tolerated for the dishes of one’s own home; for what serves every day with cold will one day serve with hot.
Earthenware (כלי חרס). It is the blind spot of the system: porous, it absorbs and does not release; הגעלה can do nothing for it. From this the Rama draws an unexpected but logical conclusion — since no remedy exists at all, we stand from the outset in the position of “after the fact”, and scouring suffices for a vessel used only with cold.
Seif 6 — Kashering part is not kashering the whole
כלי מתכות אף על פי שי״א שאם נשתמש בו איסור במקצתו נאסר כולו משום דחם מקצתו חם כולו אבל לענין הכשרו לא עלה לו הכשר עד שיכשיר כולו בין לענין הגעלה בין לענין ליבון: הגה ודוקא אם נשתמש בכולו אבל אם ידוע שלא נשתמש רק בקצתו כבולעו כך פולטו (טור):
Metal vessels: although some say that if the forbidden food was used in only part of the vessel the whole is forbidden, on the grounds that “when part of it is hot, all of it is hot” (חם מקצתו חם כולו) — as regards its kashering, however, it is not kashered until he kashers all of it, whether for הגעלה or for ליבון. Rama’s gloss: and that applies only if he used all of it; but if it is known that he used only part of it — “as it absorbed, so it expels” (כבולעו כך פולטו).
A deliberate asymmetry. To forbid, the broadest reasoning is followed: heat spreads, so the entire vessel is affected. To permit, that is not enough: the whole vessel must be kashered. This is no contradiction; it is the ordinary caution of the laws of prohibitions — expansive for concern, narrow for permission.
What the Rama is after. His gloss does not overturn the Mehaber: it isolates the case where the partial use is known. There, he says, the symmetrical principle of כבולעו כך פולטו resumes its force — the part that absorbed is the part that must expel. The Taz observes, moreover, that this gloss comes from the Tur, who disputes the Rashba whose wording the Mehaber has copied.
Group C — A knife bought from a non-Jew (seif 7)
Seif 7 — Thrust ten times into the ground, sharpen, or heat to glowing
סכין ישן בין גדול בין קטן הניקח מהעובד כוכבים אם בא להשתמש בצונן אם אין בה גומות נועצה עשרה פעמים בקרקע קשה וצריך שכל נעיצה ונעיצה תהיה בקרקע קשה לפיכך לא ינעוץ במקום שנעץ נעיצה אחרת (טור בשם הרמ״ה) ואפילו לחתוך בו דבר חריף כמו צנון סגי בהכי. (ולהשתמש בו בקביעות לא גרע משאר כלי שנוהגין להגעיל אפילו לצונן) (סברת הרב בדברי הארוך) (כמו שנתבאר) ואם יש בה גומות (או) שרוצה לחתוך בה חמין או לשחוט בה מלבנה או משחיזה במשחזת של נפחים היטב על פני כולה: הגה וי״א דהשחזה מהני רק לחתוך בה צונן אבל לא לענין חמין (ב״י בשם פוסקים) והכי נהוג לכתחלה ואם לא יוכל ללבן הסכין היטב משום הקתא ילבנו ויגעילנו אח״כ (ארוך) ומיהו אם לבנו ולא הגעילו אפילו יש בו גומות או אם הגעילו ולא לבנו ואין בו גומות וחתך בו מאכל חם לא נאסר אפילו הסכין בן יומו ואם השחיזו במשחזת היטב בכל מקום והגעילו אח״כ מהני אפילו לכתחלה כמו ליבון (מרדכי פ״ב דעבודת כוכבים וארוך) אם יוכל לנקות הגומות שבו:
An old knife, whether large or small, bought from a non-Jew: if he comes to use it with cold — if it has no pits (גומות), he thrusts it ten times into hard ground (נועצה עשרה פעמים בקרקע קשה). Each thrust must be into hard ground, and therefore he shall not thrust where he has already thrust. And even to cut a sharp food with it, such as a radish, this suffices. Rama’s gloss: and to use it permanently, it is no worse than other vessels, which are customarily scalded even for cold use. And if it has pits, or he wishes to cut hot food with it, or to perform shechita with it — he heats it to glowing (מלבנה), or sharpens it on a smiths’ whetstone, thoroughly, over its entire surface. Rama’s gloss:some say that sharpening helps only for cutting cold food and not for hot — and such is the practice at the outset. And if he cannot heat the knife to glowing properly because of the handle (הקתא), let him heat it to glowing and then scald it. Nevertheless, if he heated it to glowing without scalding it — even where it has pits — or scalded it without heating it to glowing where it has no pits, and cut hot food with it, nothing became forbidden, even if the knife is ben yomo. And if he sharpened it thoroughly on a whetstone everywhere and then scalded it, that helps even at the outset, like ליבון — if he is able to clean the pits in it.
Why a whole seif for a single object? Because the knife gathers together every difficulty of the siman: it serves sometimes with cold and sometimes with hot; its blade has pits that nothing penetrates; its handle would burn if the blade were heated to glowing; and it may be used for shechita, where the demand is at its highest. One object, four regimes.
נעיצה — thrusting the blade ten times into hard ground. This is not kashering in the full sense: it is an abrasive cleaning, which makes sense only where the forbidden matter stayed on the surface — hence for cold use, and only if the blade is smooth. The Mehaber adds two tight qualifications: hard ground, and never twice in the same spot.
גומות — the pits, chips and notches of the blade. They are the real criterion of the seif: where the surface is continuous, it can be cleaned or ground down; where it is hollowed, neither scrubbing nor whetstone reaches the bottom, and only fire remains. The very last words of the siman return to them: אם יוכל לנקות הגומות שבו.
2. Background — the mishna in Avoda Zara and the Rambam’s ladder
Seif 1 invents nothing: it restates a mishna. In the chapter Ha-sokher et ha-po‘el of tractate Avoda Zara, the mishna already lays down the principle and breaks it into three procedures:
One who buys utensils from non-Jews: that whose way is to be immersed, let him immerse; to be scalded, let him scald; to be heated to glowing in fire, let him heat it to glowing in fire. The spit and the grill are heated to glowing in fire; the knife is ground down, and it is pure.
The Shulchan Aruch follows this mishna word for word in its order: immersion (Siman 120), הגעלה (seifim 1-3), ליבון (seifim 4-6), the knife (seif 7). The two consecutive simanim of Yoreh De‘ah are, together, the commentary on this one mishna.
The Rambam, for his part, casts it as a three-rung ladder, and in that form it is easiest to retain:
Things used with cold — cups, flasks and jugs — are rinsed and immersed, and they are permitted. Things used with hot — cauldrons, kettles and water heaters — are scalded and immersed, and they are permitted. Things used by fire — spits and grills — are heated to glowing in fire until their crust flakes off, then immersed, and they are permitted.
The siman’s governing questions
What exactly is being kashered? Not dirt, but the taste absorbed into the wall. Which is why a perfectly clean vessel may remain forbidden.
How is the procedure chosen? By the use, never by the material: כדרך שנשתמש בהן העובד כוכבים כך הוא הכשרן.
What if the procedure is impossible? A knife handle, earthenware, a coated pan: the siman answers with after-the-fact remedies and sometimes with a plain “there is no remedy”.
Kashering or immersion first?הכשר then טבילה — and seif 2 discusses precisely what the reverse order is worth.
Do not confuse the two neighbouring simanim: Siman 120 deals with טבילת כלים — a change of status, which applies even to a brand-new vessel. Siman 121 deals with הכשר כלים — the removal of a forbidden taste, which concerns only a vessel already used. A second-hand metal vessel bought from a non-Jew needs both, in that order.
3. The key concepts of this siman
כְּדֶרֶךְ תַּשְׁמִישׁוֹ כָּךְ הֶכְשֵׁרוֹ — kashering follows use. The governing rule, laid down in the very first words of seif 1. It has a constant corollary: כְּבוֹלְעוֹ כָּךְ פּוֹלְטוֹ, as it absorbed, so it expels — which the Rama uses explicitly in seif 6.
הֲדָחָה וְשִׁפְשׁוּף — rinsing and scrubbing. The procedure for cold (seif 1). It draws nothing out of the wall, because nothing entered it: it removes what clings to the surface. Hence the Mehaber’s insistence on thorough scrubbing, not a mere pass under the tap.
הַגְעָלָה — scalding. The procedure for heat through liquid (seif 2): the vessel is plunged into the boiling water of a vat, and the absorbed taste comes back out. The details — temperature, size of the vat, order of the vessels — are referred to Hilkhot Pesach (seif 3).
לִיבּוּן — heating to glowing. The procedure for direct fire, with no intervening liquid: spit, grill, frying pan (seif 4), knife blade (seif 7). The Rambam gives its measure: עַד שֶׁתִּנְשַׁר קְלִפָּתָן — until their crust flakes off.
בֶּן יוֹמוֹ — a vessel “of the day”. One used with the forbidden food within twenty-four hours. Its absorbed taste is still enhancing, and therefore prohibiting. Two consequences here: a vessel that is ben yomo is not kashered (seif 2, Rama); and when a case is resolved after the fact, it is stressed that this holds even if it is ben yomo (seif 7, Rama).
חַם מִקְצָתוֹ חַם כֻּלּוֹ — “part hot, all hot”. The conductivity argument for metal, invoked in seif 6 in order to forbid the entire vessel. The Mehaber refuses to run it in the opposite direction: kashering part does not kasher the whole.
עֲרַאי וְקֶבַע — occasional and permanent. A distinction introduced by the Rama in seif 5, and probably the most operative in the siman for everyday life. What is tolerated in someone else’s home, or once, is not tolerated for one’s own dishes: the risk of drifting into hot use justifies requiring הגעלה even for cold.
כְּלִי חֶרֶס — earthenware. Porous, it absorbs without releasing: הגעלה cannot help it. From this the Rama derives a common-sense rule (seif 5): since no remedy exists, we are in the “after the fact” regime from the start, and scouring suffices where the use was only cold.
נְעִיצָה בְּקַרְקַע קָשָׁה — thrusting into hard ground. The procedure proper to the knife (seif 7): ten thrusts, each into hard ground, never twice in the same spot. An abrasive, not a kashering by heat — hence its two limits: cold use, and a blade without pits.
גּוּמּוֹת — the pits of the blade. Chips, notches and pockmarks: wherever scrubbing and whetstone cannot reach the bottom. Their presence moves the knife from the lightest regime to the heaviest — and the siman closes on them, in its very last line.
4. The three rungs — the use → kashering table
The whole siman can be read in a single column: how did the prohibition get in? The answer dictates the procedure, and nothing else does.
התשמיש
How the prohibition entered
Kashering
Seif
צונן
Cold — the prohibition stays on the surface
הדחה with thorough scrubbing, then טבילה
1
חמין
Heat through liquid — the taste enters the wall
הגעלה, then טבילה
2
על ידי האור
Direct fire, with no liquid
ליבון
4 · mishna
מחבת של טיגון
Frying — fire without water
ליבון, not הגעלה, despite Pesach
4
כלי שהגעילו במקום ליבון
Insufficient kashering
Forbidden with hot; cold permitted after the fact
5
כלי חרס
Earthenware — absorption with no remedy
No הגעלה possible; scouring if the use was cold
5 (Rama)
תיבות ושלחנות
Chests and tables — hot food possibly spilled
Custom: הגעלה at the outset; no concern after the fact
5 (Rama)
כלי כסף שחיממו בו יין
Silver vessel in which wine was warmed
Custom: הגעלה, ואין לשנות
5 (Rama)
נשתמש במקצת הכלי
Partial use, established
כבולעו כך פולטו — the part suffices
6 (Rama)
סכין בלא גומות · צונן
Smooth blade, cold use
נעיצה ten times into hard ground
7
סכין בעל גומות · או חמין · או שחיטה
Pitted blade, or hot use, or shechita
ליבון or complete grinding on a whetstone
7
סכין שהקתא מעכבת
Handle preventing a full ליבון
ליבון followed by הגעלה
7 (Rama)
Read from top to bottom, the right-hand column traces a continuous ladder: the greater the heat that brought the prohibition in, the greater the heat that must drive it out. The siman has no other logic — and that is what makes it memorable.
5. The Taz and the Shach — two key entries
The two great commentaries printed around the Shulchan Aruch of Yoreh De‘ah are the Taz (Turei Zahav, Rabbi David haLevi Segal, 1586-1667) and the Shach (Siftei Kohen, Rabbi Shabtai haKohen, 1621-1662). On this siman both stop at exactly the same place: the border between kashering and immersion.
A key entry from the Taz
Taz s.k. 1 — why the order of the two operations matters
דאין הטבילה צורך ההגעלה אלא שיצא בטבילה מטומאה לטהרה
— ט״ז יו״ד קכ״א ס״ק א
For the immersion is not a requirement of the הגעלה: it is there so that it should pass, through immersion, from impurity to purity.
In one line the Taz separates two operations that are constantly conflated. הגעלה removes a forbidden taste; טבילה effects a change of status. Neither serves the other — and it is precisely because they are independent that the Mehaber can allow the reverse order after the fact.
A key entry from the Shach
Shach s.k. 5 — immerse again, but without a blessing
ונראה דיש לחזור ולהטבילן בלא ברכה
— ש״ך יו״ד קכ״א ס״ק ה
And it appears that one should immerse them again — without a blessing.
The וי״א of seif 2 required a second immersion for a vessel immersed before its הגעלה. The Shach concurs — but withholds the blessing, since according to the first opinion a valid immersion has already taken place. It is the same signature as in Siman 120: the act is never given up, the blessing is.
6. The Rama’s gloss (הגה) — the line of received practice
The Rama intervenes in five of the seven seifim. His manner here is very recognisable: he reports fewer opinions than practices, and seals them with a formula — והכי נוהגין, ואין לשנות, והכי נהוג לכתחלה.
On seif 1 — casks sealed with fat
A gloss that looks marginal, yet is faithful to the governing rule: if the fat does not touch the wine, no taste entered and there is nothing to kasher. The Rama here merely records a local custom and supplies its reason.
On seif 2 — the safeguards of הגעלה
Three technical qualifications, all negative: no kashering of a vessel that is בן יומו; no use of the הגעלה water; and shaving the vessel down does not substitute for הגעלה. All three say the same thing: an absorbed taste cannot be circumvented.
On seif 5 — the master gloss
The longest in the siman. It introduces the pair עראי / קבע, extends the custom of הגעלה to silver vessels and even to chests and tables, then comes to rest on earthenware, for which it accepts scouring. Three times it separates what holds at the outset from what holds after the fact.
On seif 6 — partial use
The Rama restricts the Mehaber’s stringency to the case where all of the vessel was used, and restores כבולעו כך פולטו where partial use is established. The Taz points out that this position is in truth that of the Tur, in dispute with the Rashba.
On seif 7 — the knife, between the ideal and the remedy
The most practical gloss of the siman: what is done at the outset (sharpening only for cold), what is done when the handle prevents ליבון, and what remains valid after the fact — even with pits, even ben yomo.
One line runs through these five glosses: the Rama does not dispute the Mehaber’s rule, he shows its edges — what is actually done, what is tolerated once, and what is not tolerated as a settled practice. To read the siman without the glosses is to know its principle without knowing how to apply it.
7. Practical cases today
Case 1 — A set of pots bought second-hand
Metal pots in which non-kosher food was cooked in water: this is the case of seif 2. Two operations, in this order — הגעלה, then טבילה (Siman 120). And one condition of timing from the Rama’s gloss: the vessel must not be בן יומו, that is, one must wait twenty-four hours after its last use.
Case 2 — The frying pan
Seif 4 is explicit: frying calls for ליבון, not הגעלה, and the fact that הגעלה suffices on Pesach proves nothing for other prohibitions. But a genuine ליבון warps or destroys most modern pans and ruins any non-stick coating. This is a case where the practical answer is usually do not kasher, replace — and where one asks a Rav before attempting anything.
Case 3 — A rented kitchen, a holiday apartment
This is precisely the situation of seif 5, with its עראי / קבע distinction. For occasional use the Rama permits cold after rinsing and scrubbing; for permanent use he requires more, out of concern for drifting into hot use. Ovens, hobs and surfaces belong in any case to ליבון: such situations are arranged in advance with a Rav, not improvised the night before departure.
Case 4 — The knife and the board
A second-hand knife with a smooth blade, intended for cold use: seif 7 permits נעיצה, ten times into hard ground. But two reservations immediately hedge it in: the blade must have no גומות, and the Rama refuses this regime for permanent use. In a kitchen a knife sooner or later serves with hot food: in practice, therefore, the heavier regime — ליבון — applies.
Case 5 — Earthenware and porcelain
Seif 5 states it plainly: for כלי חרס, הגעלה is impossible. There is a solution only in the narrow case the Rama envisages — a use that was cold alone, for which thorough scouring and rinsing suffice. For everything else, earthenware used with hot food cannot be recovered.
8. Summary of Siman 121
In one sentence: a vessel bought from a non-Jew and already used is kashered according to the way it was used — cold by rinsing, hot by הגעלה, fire by ליבון — and the seven seifim do no more than spell out what becomes of that rule when a procedure is impossible, partial, or already wrongly performed.
Memory table
The question
The criterion
Where
Which procedure?
The use the non-Jew made of it, not the material
seif 1
Cold use?
Rinsing with thorough scrubbing
seif 1
Hot use?
הגעלה, then טבילה for metal
seif 2
In what order?
הכשר then טבילה; the reverse is disputed
seif 2
Where is the procedure set out?
Written once and for all in Hilkhot Pesach
seif 3
The frying pan?
ליבון — Pesach is no proof, hetera bala
seif 4
Insufficient kashering?
Forbidden with hot; cold permitted after the fact
seif 5
Occasional or permanent?
עראי / קבע — the fear of drift
seif 5 (Rama)
Only part of it?
All is forbidden; and one does not kasher by halves
seif 6
The knife?
גומות or not, cold or hot, shechita or not
seif 7
Comprehension questions
Why does kashering depend on the use and not on the material of the vessel? Which phrase of seif 1 says so?
A vessel was immersed before being scalded. What does the Mehaber say, what does the וי״א say, and how does the Shach decide?
Why does the frying pan need only הגעלה for chametz, yet require ליבון for other prohibitions?
Seif 6 reasons from חם מקצתו חם כולו in order to forbid, but refuses the converse reasoning in order to permit. Is that a contradiction?
What distinguishes, in seif 5, עראי use from קבע use — and what concrete concern justifies the distinction?
For which three different reasons can the knife of seif 7 move from the regime of נעיצה to that of ליבון?
Going further
If you wish to go deeper into this siman:
📚 Level 2 — Lamdan: the pilpul — hetera bala against issura bala, the maḥloket of the Rashba, the Ra’ah and the Tur on partial ליבון, and the sugya in Avoda Zara on the knife
✨ Level 3 — Synthesis: the comparative tables (use, procedure, material) and a rapid review of the 7 seifim
⚖️ Level 4 — Halakha lema‘aseh: the practical ruling (Shach, Taz, Pri Ḥadash, Pitchei Teshuva) and contemporary poskim
The sources for this level can be consulted on Sefaria: