Yesterday’s mishnah introduced a discussion of the biblical prohibition on consuming the sciatic nerve. The origin for this prohibition is Genesis 32, in which Jacob’s all-night wrestling match with an angel ends when the latter injures his hip. In commemoration of this moment, the Torah explains, Jews do not eat the gid nasheh that is located in the hip. This has long been understood as referring to the sciatic nerve.
The mishnah gave some parameters for fulfilling this commandment, including a statement that it refers to the sciatic nerve on both sides, left and right. In today’s Gemara, however, we learn that not everyone shared this view:
The mishnah is not in accordance with the opinion of Rabbi Yehuda, as it is taught in a beraita that Rabbi Yehuda says: The prohibition of the sciatic nerve applies only to the sciatic nerve in one of the animal’s thighs, and logic dictates that it is the right.
Rabbi Yehuda believes two things: First, there’s only one sciatic nerve the Torah prohibits. Second, the prohibited nerve is the one on the right side. The Gemara finds his phrasing curious.
A dilemma was raised before the sages: … What does Rabbi Yehuda mean when he says that “logic dictates”? He means the logic of the Torah. Or perhaps he is uncertain, and accordingly, he means that logic inclines.
There are two different ways of understanding Rabbi Yehuda’s statement. One is that he believes the Torah clearly dictates that the prohibition on the sciatic nerve applies to the right thigh only. The other is that he’s using his own logic to deduce which side is prohibited, which would make him less sure. The question becomes: How certain is Rabbi Yehuda in his position?
Come and hear from a mishnah: The bones, sinews and leftover meat of the paschal offering should all be burned on the 16th of Nisan. And we discussed it: What are the circumstances in which these sinews must be burned? If we say they are sinews of meat, let one eat them. And if they are sinews that were left over and not eaten, that is the case of leftover meat. Rather, the mishnah is referring to sinews of the neck. But if they are not meat, let one simply discard them.
We learned in Tractate Pesachim that edible parts of the paschal sacrifice that are not eaten by the deadline must be burned. This mishnah from Pesachim mentions sinews, but the sages are confused by its inclusion. If they’re normal, edible sinews, they likely were eaten and do not require disposal. And if they are not edible, they would not assume the special status of leftover sacrificial meat (notar) and require burning. So what are these sinews the mishnah says we must burn?
Rav Hisda said: The mishnah’s mention of sinews is necessary only in order to teach the halakhah of the sciatic nerve in accordance with the opinion of Rabbi Yehuda, who said: The prohibition of the sciatic nerve applies only to the sciatic nerve in one of the animal’s thighs.
Granted, if you say that Rabbi Yehuda is uncertain as to which thigh is prohibited, it works out well. But if you say that it is obvious to Rabbi Yehuda that the sciatic nerve of only the right thigh is forbidden, let him eat the sciatic nerve of the permitted left thigh, and let him throw away only the sciatic nerve of the forbidden right thigh.
Here’s how Rav Hisda proposes we explain the inclusion of sinews in the mishnah from Pesachim: “Sinews” refers specifically to the sciatic nerve. The mishnah is in accordance with Rabbi Yehuda, who believes the sciatic nerve of only one thigh is prohibited. When he said in a beraita earlier on today’s daf that “logic dictates” this thigh is on the right, he was merely referring to his own deduction. Therefore, since we’re uncertain which of the sciatic nerves is permitted and which is forbidden, in the case of the paschal offering we burn both. By contrast, if Rabbi Yehuda were certain that only the right thigh is prohibited, that sciatic nerve could be discarded in any manner and the other could be consumed. What have we shown, therefore, according to Rav Hisda? That Rabbi Yehuda is not certain which thigh’s sciatic nerve is forbidden.
Ultimately, this argument is dismissed. After a series of further attempted proofs, the Gemara finally concludes that Rabbi Yehuda is indeed certain the prohibition applies specifically to the right thigh because it derives from the Torah. Two possible derivations are suggested. The first: The matter-of-fact mention of “the thigh” in the Torah clearly indicates the more important thigh. The second: When one wrestles, as the angel did with Jacob, it is more likely their right arm would reach around the person before them and grab the right leg — so that’s surely where Jacob was injured.
This is a great example of the Gemara exploring not just the details of a given halakhah, but the meta question of how to determine the nature of a rabbi’s reasoning. The focus on today’s daf quickly shifts from the dispute between the rabbis and Rabbi Yehuda (over whether one or both sciatic nerves are forbidden) to a question about Rabbi Yehuda’s level of certainty in his own halakhah.
Read all of Chullin 90 on Sefaria.
This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on July 29, 2026. If you are interested in receiving the newsletter, sign up here.
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