Talmud - Pesahim 83b פסחים פ״ג ב׳

when one finds them in piles, and he sees that some of them have had their marrow removed. If these bones are bones of offerings to which the prohibition of breaking a bone does not apply, one can assume that the owner removed the marrow from all the bones before the marrow became leftover and ate it, and they do not require burning.

On the other hand, with regard to the bones of the Paschal lamb, to which the prohibition of breaking a bone does apply, perhaps the owner removed the marrow from these, and from those he did not remove the marrow, and they require burning. Therefore, although one needs to check all the bones of the Paschal lamb he finds to ensure that they do not have marrow left in them, he does not need to burn them due to the unconfirmed possibility that the marrow was removed after it became leftover. The bones would need to be burned only if there was still marrow in them or if one knew for certain that they had served as a base for leftover sacrificial meat.

Rav Yehuda said that Rav said: All the sinews in an animal are considered like meat. Therefore, one can fulfill his obligation to eat the Paschal lamb by eating them and one can register for them, except for the sinews of the neck, which are so hard that they are not considered meat.

We learned in the mishna: The bones, and the sinews, and the leftover shall be burned on the sixteenth. The Gemara asks: What are the circumstances in which these sinews must be burned? If we say they are sinews of meat, let us eat them. Why are they burned? And if they are sinews that were left over and not eaten for some other reason, they are leftover, so why does the mishna list sinews separately? Rather, it is obvious that the mishna is referring to sinews of the neck, which are different than other sinews and are therefore mentioned separately.

Granted, if you say they are meat, due to that they require burning; but if you say they are not meat, why do they require burning? One should simply discard them like other waste. Rav Ḥisda said: The mishna’s mention of sinews is necessary only for the sciatic nerve, in accordance with the opinion of Rabbi Yehuda.

As it was taught in a baraita that Rabbi Yehuda said: The prohibition to eat the sciatic nerve according to Torah law applies only to the sciatic nerve in one of the animal’s thighs, and not to both, and logic dictates that it is the right thigh. However, since there is no absolute proof that this is correct, the sciatic nerve must be removed from both sides. Although in theory the forbidden sciatic nerve may be discarded and the permitted one may be eaten, since there is uncertainty as to which one is permitted, neither of them may be eaten. Both must be burned.

The Gemara asks: Shall we then conclude that Rabbi Yehuda was uncertain about which sciatic nerve is forbidden? The Sages were unsure whether Rabbi Yehuda was absolutely convinced that it is the sciatic nerve from the right side that is forbidden, or if he was saying that this would seem likely to be the case, but he was not certain. As, if it were clear to him that it is the sciatic nerve from the right thigh that is forbidden, the proper procedure would be different: The one that is permitted we should eat, and the one that is forbidden we should discard. Why should he require burning?

Rav Ika bar Ḥinnana said, in response to this attempted proof: The mishna addresses a case where the two sciatic nerves were known, but in the end became mixed together. In other words, at first it was known which was the forbidden right nerve and which was the permitted left nerve. However, they were then mixed together and can no longer be identified. Therefore, due to the uncertainty, they must both be burned.

Rav Ashi said: The mishna’s ruling that the sinews must be burned is necessary only with regard to the fat of the sciatic nerve, as it was taught in a baraita: The fat around the sciatic nerve is permitted according to Torah law, but the Jewish people are holy and treat it as forbidden. Since it is permitted according to Torah law, it has the status of meat and may not be simply discarded. However, since the Jewish people treat it as forbidden, they do not eat it even from the Paschal lamb. Therefore, it is left until after the time when the meat may be eaten and burned in accordance with the general halakha of leftover.

Ravina said: This discussion pertains to the outer nerve, and it is in accordance with that which Rav Yehuda said that Shmuel said, as Rav Yehuda said that Shmuel said: There are two sinews in the sciatic nerve: The inner sinew that is next to the bone is forbidden according to Torah law, and one is liable to be flogged for eating it. The outer sinew that is next to the meat is forbidden by rabbinic law, and therefore one is not liable to be flogged for eating it. Since the outer sinew is permitted according to Torah law, it attains the status of leftover when it is not eaten.

It was taught in the mishna that if the sixteenth of Nisan occurs on Shabbat, the burning of the leftover does not override Shabbat, and they are burned on the seventeenth. The Gemara asks: And why isn’t the leftover of the Paschal lamb burned on the Festival day itself? The positive mitzva to burn the leftover should come and override the prohibition that prohibits the performance of labor on Festivals.

Ḥizkiya said, and similarly, one of the Sages in the school of Ḥizkiya taught: The verse states: “And you shall not leave any of it until morning; and that which remains of it until morning you shall burn with fire” (Exodus 12:10). As there is no need for the verse to state “until morning,” and repeating that phrase adds nothing to the verse, what is the meaning when the verse states “until morning”? It is to give it a second morning for its burning. In other words, it comes to teach that the mitzva to burn the leftover does not apply on the first morning, i.e., the morning of the Festival when they become prohibited to eat, but on the second morning, the sixteenth of Nisan. However, when the sixteenth falls on Shabbat, the burning is delayed until the seventeenth.

Abaye said: The reason is because the verse states: “The burnt-offering of each Shabbat on its Shabbat in addition to the continual burnt-offering and its libation” (Numbers 28:10). This indicates that the burnt-offering of Shabbat may be offered on the altar on Shabbat or burned if it is disqualified, but not the burnt-offering of a weekday on Shabbat, and not the burnt-offering of a weekday on a Festival. It is derived from here that one may not burn anything on Shabbat that is not an obligation of that day.

Rava said a different reason: The verse states concerning Festivals: “And on the first day there shall be a sacred convocation; no kind of labor shall be done on them, save that which every man must eat, only that may be done for you” (Exodus 12:16). From this verse one can infer the following: That, i.e., the food itself, you may prepare, but you may not perform acts that facilitate its preparation, which must be done beforehand. The word only is also exclusive; it indicates that only food preparation is permitted,

Traduction : The William Davidson digital edition of the Koren Noé Talmud, with commentary by Rabbi Adin Even-Israel Steinsaltz.

Pesachim 83b examines burning rules for Paschal lamb bones and marrow, and debates whether neck sinews count as edible meat.