עַל־כֵּ֡ן לֹֽא־יֹאכְל֨וּ בְנֵֽי־יִשְׂרָאֵ֜ל אֶת־גִּ֣יד הַנָּשֶׁ֗ה אֲשֶׁר֙ עַל־כַּ֣ף הַיָּרֵ֔ךְ עַ֖ד הַיּ֣וֹם הַזֶּ֑ה כִּ֤י נָגַע֙ בְּכַף־יֶ֣רֶךְ יַעֲקֹ֔ב בְּגִ֖יד הַנָּשֶֽׁה׃
Therefore the children of Yisrael do not eat the sciatic nerve that is on the hollow of the thigh to this day, because he touched the hollow of Yaakov’s thigh on the sciatic nerve.
Mishnah Chullin 7:6 (as discussed in the Bavli, Chullin 100b).
נוהג בטהורה, ואינו נוהג בטמאה. רבי יהודה אומר: אף בטמאה.
“[The prohibition of] the sciatic nerve applies to a pure animal, but does not apply to an impure animal. Rabbi Yehudah says: it applies even to an impure animal.”
The Mishnah records the dispute over whether the prohibition applies to the sciatic nerve of a non-kosher animal; the surrounding Gemara analyzes Rabbi Yehudah’s position.
Halakhic derash on the extent of the prohibition (Bavli).
The prohibition of the gid ha-nasheh applies broadly, not only to the animals of the patriarchal household.