His Incest with Thamar - Genesis 38
The following sketch from the life of Judah is intended to point out the origin of the three leading families of the future princely tribe in Israel, and at the same time to show in what danger the sons of Jacob would have been of forgetting the sacred vocation of their race, through marriages with Canaanitish women, and of perishing in the sin of Canaan, if the mercy of God had not interposed, and by leading Joseph into Egypt prepared the way for the removal of the whole house of Jacob into that land, and thus protected the family, just as it was expanding into a nation, from the corrupting influence of the manners and customs of Canaan. This being the intention of the narrative, it is no episode or interpolation, but an integral part of the early history of Israel, which is woven here into the history of Jacob, because the events occurred subsequently to the sale of Joseph.
About this time, i.e., after the sale of Joseph, while still feeding the flocks of Jacob along with his brethren (Gen 37:26),
Judah separated from them, and went down (from Hebron, Gen 37:14, or the mountains) to Adullam, in the lowland (Jos 15:35), into the neighbourhood of a man named Hirah. “He pitched (his tent, Gen 26:25) up to a man of Adullam,” i.e., in his neighbourhood, so as to enter into friendly intercourse with him.