Zevachim Daf 57 זבחים דַף 57

A Baraisa presents the source that a bechor is eaten for two days and a night: ובשרם יהיה לך כחזה התנופה וכשוק הימין – and their meat shall be for you like the breast of the waving and the right thigh. This creates a היקש between שלמים and בכור, teaching that just as שלמים is eaten for שני ימים ולילה אחד, bechor is as well. The Chochomim in Kerem b’Yavneh were asked how many days a bechor is eaten; Rebbe Tarfon said it is eaten for two days, and a new student, Rebbe Yose HaGlili, asked for his source. Rebbe Tarfon explained that he derives it from שלמים, since they are both קדשים קלים, but Rebbe Yose asked that perhaps it should be compared with a חטאת and אשם (which are eaten for one day), since they are similarly gifts for Kohanim. This debate continued until Rebbe Tarfon withdrew, and Rebbe Akiva presented the above היקש with שלמים. Rebbe Yose HaGlili persisted that perhaps the היקש is with the חזה ושוק of a תודה, which is eaten for one day, and Rebbe Akiva instead darshened the extra words "יהיה לך" – it shall be yours, teaching: הוסיף הכתוב הויה אחרת בבכור – the passuk added another “being” to bechor, to be eaten for two days.

When the above conversation was related to Rebbe Yishmael, he said to go tell Rebbe Akiva, “You made a mistake [in conceding to Rebbe Yose HaGlili’s challenge].” Since the source that the חזה ושוק of תודה are given to Kohanim is itself [a היקש from] shelamim, [וכי] דבר הלמד בהיקש חוזר ומלמד בהיקש – can something which derives its law from a hekesh in turn teach that law through another hekesh? Therefore, Rebbe Akiva was correct to be מקיש bechor with the חזה ושוק of שלמים, and should not have conceded to the possibility to be מקיש to תודה. The Gemara explains their disagreement: מר סבר הימנו ודבר אחר הוי היקש – [Rebbe Yishmael] holds that a law learned partially from it (the passuk) and partially from something else is considered something learned from a hekesh, and cannot be חוזר ומלמד elsewhere, but Rebbe Akiva holds "הימנו ודבר אחר" is not considered learned from a hekesh. Case in point, the fact that a תודה’s חזה ושוק are given to Kohanim is derived from a hekesh, but their requirement to be eaten in one day is not. Two challenges are posed to Rebbe Yishmael’s opinion, and are answered.

The Mishnah on the previous Daf taught that a korban pesach may only be eaten until חצות. Rav Yosef says this reflects the opinion of Rebbe Elazar ben Azaryah, who said that the Torah says to eat the pesach "בלילה הזה" – on this night, and מכת בכורות is also described as occurring "בלילה הזה", teaching: מה להלן עד חצות – just as there (מכת בכורות) did not occur until midnight, אף כאן עד חצות – so too here, the pesach may be eaten until midnight. Rebbe Akiva objected that the passuk says ואכלתם אותו בחפזון – and you shall eat it in haste, implying עד שעת חפזון – until the hour of haste (the morning, when the Jews would hastily leave מצרים)!? Instead, Rebbe Akiva says that "בלילה הזה" restricts the pesach not to be eaten the next day (in contrast with other korbanos). Abaye suggested that the Mishnah can agree with Rebbe Akiva, because its requirement to eat the pesach before חצות can be מדרבנן, ולהרחיק מן העבירה – to distance him from transgression by delaying until it becomes נותר. Rav Yosef replied that the Mishnah’s language, "אלא עד חצות" – that it may be eaten only until midnight compares it to the Mishnah’s other restrictions (e.g., it is “only” eaten roasted), which are all דאורייתא.