וַיִּקְנֵהוּ פּוֹטִיפַר סְרִיס פַּרְעֹה אָמַר רַב שֶׁקְּנָאוֹ לְעַצְמוֹ בָּא (גַּבְרִיאֵל) [מִיכָאֵל] וְסֵירְסוֹ בָּא גַּבְרִיאֵל וּפֵירְעוֹ מֵעִיקָּרָא כְּתִיב פּוֹטִיפַר וּלְבַסּוֹף פּוֹטִיפֶרַע
The continuation of that verse states: “And Potiphar, an officer [seris] of Pharaoh’s, the captain of the guard, an Egyptian, bought him from the hand of the Ishmaelites, who had brought him down there” (Genesis 39:1). Rav says: He purchased the handsome Joseph for himself, for the intended purpose of homosexual intercourse, but was unable to fulfill his desires, as the angel Gabriel came and castrated Potiphar [seireso]. Then Gabriel came again and further mutilated him [ fero] in the same part of his body. This is alluded to in the verses that write Potiphar’s name differently: Initially, it is written “Potiphar” (Genesis 39:1) and in the end it is written “Poti-phera” (Genesis 41:45). The change in his name indicates that a part of himself was mutilated.