TANAKH SOURCES:
(טו) וַיִּקְח֤וּ הָֽאֲנָשִׁים֙ אֶת־הַמִּנְחָ֣ה הַזֹּ֔את וּמִשְׁנֶה־כֶּ֛סֶף לָקְח֥וּ בְיָדָ֖ם וְאֶת־בִּנְיָמִ֑ן וַיָּקֻ֙מוּ֙ וַיֵּרְד֣וּ מִצְרַ֔יִם וַיַּֽעַמְד֖וּ לִפְנֵ֥י יוֹסֵֽף׃ (טז) וַיַּ֨רְא יוֹסֵ֣ף אִתָּם֮ אֶת־בִּנְיָמִין֒ וַיֹּ֙אמֶר֙ לַֽאֲשֶׁ֣ר עַל־בֵּית֔וֹ הָבֵ֥א אֶת־הָאֲנָשִׁ֖ים הַבָּ֑יְתָה וּטְבֹ֤חַ טֶ֙בַח֙ וְהָכֵ֔ן כִּ֥י אִתִּ֛י יֹאכְל֥וּ הָאֲנָשִׁ֖ים בַּֽצׇּהֳרָֽיִם׃
(15) So the agents took that gift, and they took with them double the money, as well as Benjamin. They made their way down to Egypt, where they presented themselves to Joseph. (16) When Joseph saw Benjamin with them, he said to his house steward, “Take those men into the house; slaughter and prepare an animal, for those men will dine with me at noon.”
GEMARA SOURCES:
ואמר רבי יוסי ברבי חנינא מאי דכתיב (בראשית מג, טז) וטבוח טבח והכן פרע להן בית השחיטה והכן טול גיד הנשה בפניהם כמ"ד גיד הנשה נאסר לבני נח
And Rabbi Yosei, son of Rabbi Ḥanina, also said: What is the meaning of that which is written: “And when Joseph saw Benjamin with them, he said to the steward of his house: Bring the men into the house, and slaughter the animals, and prepare the meat; for the men shall dine with me at noon” (Genesis 43:16)? Joseph commanded his steward: Expose the place of the slaughter on the neck of the animal to them so that the brothers will know that it is being slaughtered correctly. “And prepare” teaches that Joseph instructed the steward to remove the sciatic nerve in their presence so that the brothers would know that it had been fully removed. The Gemara comments that this opinion is according to the one who said that the sciatic nerve was forbidden to the children of Jacob even before the Torah was given, when they still had the status of descendants of Noah.
THE TAKEAWAY: A SIGNAL OF KINSHIP
(לב) וַיִּֽזְרַֽח־ל֣וֹ הַשֶּׁ֔מֶשׁ כַּאֲשֶׁ֥ר עָבַ֖ר אֶת־פְּנוּאֵ֑ל וְה֥וּא צֹלֵ֖עַ עַל־יְרֵכֽוֹ׃ (לג) עַל־כֵּ֡ן לֹֽא־יֹאכְל֨וּ בְנֵֽי־יִשְׂרָאֵ֜ל אֶת־גִּ֣יד הַנָּשֶׁ֗ה אֲשֶׁר֙ עַל־כַּ֣ף הַיָּרֵ֔ךְ עַ֖ד הַיּ֣וֹם הַזֶּ֑ה כִּ֤י נָגַע֙ בְּכַף־יֶ֣רֶךְ יַעֲקֹ֔ב בְּגִ֖יד הַנָּשֶֽׁה׃
(32) The sun rose upon him as he passed Penuel, limping on his hip. (33) That is why the children of Israel to this day do not eat the thigh muscle that is on the socket of the hip, since Jacob’s hip socket was wrenched at the thigh muscle.