“A nd he took Machalas the daughter of Yishmael…in addition to his other wives as a wife.” (Bereishis 28:9)
Rashi quotes Bereishis Rabbah (67:13) that Eisav added wickedness upon his wickedness for he did not divorce his first wives.
Chazal tell us that Eisav saw that the daughters of Canaan were not pleasing in his father’s eyes so he went to Yishmael. Rabi Yehoshua ben Levi says that Eisav even decided to convert. Therefore this wife is called Machalas because Hashem forgave him for all his sins.
Says Rav: If he had gotten rid of his first wives it would have been a good thing. But here he added “pain upon pain ” because he didn’t divorce the first ones. (Rav Meir Rubman Zichron Meir)
