Bereishis Rabbah 93:6.
Sefaria — Bereishis Rabbah 93:6
גְּשׁוּ נָא אֵלַי וַיִּגָּשׁוּ — הֶרְאָה לָהֶם אֶת הַמִּילָה.
English: “Please come near to me, and they came near” — he showed them the circumcision.
On the daf / in context: Bereishis Rabbah 93:6 says Yosef’s brothers did not believe his identity until he showed them the milah. The longer surrounding passage belongs to 93:8; the milah statement itself is in 93:6.
What Is Learned: Yosef used the covenantal sign to establish his identity.