Genesis 19:34-38

34On the following day, the firstborn said to the younger, “Look, I slept last night with my father; let’s make him drink wine tonight too, then you go in and sleep with him, so that we may keep 1our family alive through our father.”

35So they had their father drink wine that night too, and the younger got up and slept with him; and he did not know when she lay down or got up.

36And so both of the daughters of Lot conceived by their father.

37The firstborn gave birth to a son, and named him 2Moab; he is the father of the Moabites to this day.

38As for the younger, she also gave birth to a son, and named him Ben-ammi; he is the father of 3the sons of 4Ammon to this day.