Kabbalah sur Les Nombres 23:7

He said to him, Where did Bilaam learn everything that he did and all that he knew? He said to him, He learned it from his father. But in "the mountains of the east" (Num. 23:7), in the land of the east, he learned the enchantments and kinds of magic, for in these mountains abide the angels Aza and Azael, whom the Holy One, blessed be He, caused to fall from heaven (because they denounced the creation of man). They are tied in chains of iron there and reveal spells to men. This is where Bilaam gained knowledge, as it is written, "Balak the king of Moab has led me from Aram, out of the mountains of the east" (Ibid.) (where Aza and Azael are).