Genesis 19:33-38

That night the two girls got their father drunk, and the older daughter went and had sexual relations with him. But Lot did not know when she lay down or when she got up. The next day the older daughter said to the younger, “Last night I had sexual relations with my father. Let’s get him drunk again tonight so you can go and have sexual relations with him, too. In this way we can use our father to have children to continue our family.” So that night they got their father drunk again, and the younger daughter went and had sexual relations with him. Again, Lot did not know when she lay down or when she got up. So both of Lot’s daughters became pregnant by their father. The older daughter gave birth to a son and named him Moab. He is the ancestor of all the Moabite people who are still living today. The younger daughter also gave birth to a son and named him Ben-Ammi. He is the father of all the Ammonite people who are still living today.