What did (Jacob) do? He wrote the Holy Name upon a golden plate, and suspended it about her neck and sent her away. She went her way. Everything is revealed before the Holy One, blessed be He, and Michael the angel descended and took her, and brought her down to Egypt to the house of Potiphera; because Asenath was destined to become the wife of Joseph. Now the wife of Potiphera was barren, and (Asenath) grew up with her as a daughter. When Joseph came down to Egypt he married her, as it is said, "And he gave him to wife Asenath the daughter of Potiphera priest of On" (Gen. 41:45).
Marriage of Asenath of Joseph
Pirkei DeRabbi Eliezer 38:2