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.
Torah Temimah points to Chullin 89b–90a.
גיד הנשה יש בו בנותן טעם או אין בו בנותן טעם? מחלוקת תנאים.
Does the sciatic nerve impart taste or does it not impart taste? There is a dispute among the Tannaim.
The Gemara debates whether the gid itself gives taste to the surrounding meat.
Derash on the physical properties relevant to the prohibition (Bavli).
There is a Tannaitic dispute whether the sciatic nerve itself imparts flavor.