Masechet Chulin Perek Zayin Mishnah Vav. The Mishnah says that Gid Hanashe (sciatic nerve) applies only to a situation involving a kosher (ritually fit) animal, but does not apply to a situation involving a non-kosher animal. That is the Isur (prohibition) of Gid Hanashe. It is only spoken about in terms of a kosher animal. Therefore, if a person eats the Gid Hanashe of a kosher animal, he would receive Malkut (lashes) for that. If he ate the Gid Hanashe of a non-kosher animal, he would still receive Malkut for eating the meat of a non-kosher animal, but he would not receive a second set of lashes for eating the Gid Hanashe.
Says Rabbi Yehuda: The Halacha (Jewish law) is even for a non-kosher animal. Says Rabbi Yehuda, if a person ate the Gid Hanashe of a non-kosher animal, they would receive two sets of Malkut: one for eating the meat of a non-kosher animal, and a second one for eating a Gid Hanashe. Says Rabbi Yehuda. He brings support, a rationale for his logic: the mitzvah (commandment) was given from the time of Yaakov Avinu's children. They were commanded in the Isur of Gid Hanashe because the story goes that when Yaakov was hit by the angel on the hip, as a remembrance of that, of Yaakov's struggle with the angel, we do not eat the Gid Hanashe going forward. So in the time of the Avot (forefathers), of the sons of Yaakov, this prohibition was given, and there was no Isur against eating a non-kosher animal at that time. It was permitted for them to eat it. Therefore, it must be referring to a non-kosher animal as well. That's the idea Rabbi Yehuda.
The rabbis respond to him: “No, it was not forbidden during Gid Hanashe, the time of Yaakov Avinu's sons. The prohibition against eating the Gid Hanashe was only said at Har Sinai. The prohibition was only said there for the first time, and it was placed within the story of Yaakov's fight with the angel. Therefore, we cannot use that Pasuk (verse) or that story to prove Rabbi Yehuda's point.” Rabbi Yehuda...