By Rabbi Shmuel Wise

A review of some of this week’s daf yomi key concepts (Pesach – Avodah Zara)


How does one kasher a grill for Pesach?


Lo and behold, the daf that falls out on the second day of Pesach this year (76a) provides a fascinating insight on this subject. The Mishnah on 75b taught us how to kasher food utensils that were used by idolaters. In order to purge the vessel walls from any forbidden absorptions, heat is applied to them. More specifically, one must heat up the vessel with the same form of heat that is used to cook with the vessel in question. So for a pot, one kashers the vessel with boiling water; for a grill, one kashers with an actual flame.

The Gemara on 76a notes that our Mishnah appears to conflict with the Mishnah in Zevachim which deals with the issue of kashering the vessels used to cook sacrificial meat. The reason kashering was necessary for these vessels is based on the law of nossar, which says that meat of a korban (depending on the particular sacrifice) becomes severely prohibited 1–2 days after the sacrifice was brought. This presents a problem — the sacrifice you are cooking today might be absorbing flavor from a nossar sacrifice of yesterday!

Hence, the sacrificial cooking utensils must constantly be kashered. The conflict arises from the Mishnah’s description of how to kasher the Beis Ha-Mikdash’s grill: one applies hot water. This would appear to contradict our Mishnah’s teaching that a grill can only be kashered with fire.

Several resolutions are suggested, but our focus is on the one offered by R’ Sheishes. R’ Sheishes draws a distinction by pointing out that at the time of absorption, the sacrificial meat was perfectly permitted; only upon the passage of time did that absorption become nossar and thus prohibited. Because of this factor, a lighter form of kashering, through boiling water, is acceptable.

The Gemara is initially at a loss to understand why this should make any difference. Once that sacrificial absorption becomes prohibited (with a prohibition of kareis, mind you) we seem to be dealing with an equal problem to that of a vessel with an absorption from non-kosher food. So if it takes fire to extract non-kosher, that’s what it should take to expel nossar, too!

However, R’ Ashi upholds R’ Sheishes’s reasoning by arguing that the status at the time of absorption is halachically meaningful. That is, the fact that by the time this sacrificial absorption became a problem the actual food it derived from no longer existed is a valid basis to lower the standard for what needs to be done to satisfactorily expel that absorption.

This halachically accepted theory of R’ Sheishes provides a potential leniency in the process of koshering a chametzdik grill (or similar utensil where a direct flame is used) for Pesach. The chametz absorption, just like the sacrifice, was perfectly permitted at the time of absorption. Only after the passage of time (i.e. upon the arrival of Pesach) did this absorption become a problem.

As such, some authorities argue that we can allow the less intense koshering method of boiling water for something like a chametzdik grill. Other authorities disagree, arguing that regarding the sacrificial utensils, one would not call the absorption nossar at the time it got absorbed — as opposed to chametz, which we would refer to as chametz (which just means a leavened product) from the beginning, even if its prohibition has not yet been activated.

Practically speaking, the Shulchan Aruch (451:4) rules like the stringent view, though the Mishnah Berurah there says that in situations where other mitigating factors can be added, we can rely on the lenient view.

Go figure — a gem on hilchos Pesach buried toward the end of Avodah Zara; this is the way of the Torah!

Rabbi Wise is maggid shiur of Real Clear Daf (, a website and mobile app that offers free audio shiurim and other resources to assist your journey through Shas. He is also the director of Tehillim Together (, a mobile app (for iOS and Android) that offers a translated sefer Tehillim and facilitates Tehillim groups. To be a sponsor or to reach Rabbi Wise, please write to or call 855-ASK-RCD-1 (275-7231).


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