Genesis 19:34-38

34On the following day, the firstborn said to the younger, “See! I slept with my father last night. Let’s make him drink wine tonight as well. Come on! Sleep with him so that we’ll keep the seed from our father alive.”

35So they made their father drink wine that night as well, and the younger got up and lay down with him and he did not know that she lay down and got up.

36So Lot’s two daughters become pregnant by their father.

37Then the firstborn gave birth to a son and named him Moab: he is the ancestor of the Moabites to this day.

38The younger also gave birth to a son and named him Ben-Ammi: he is the ancestor of the sons of Ammon to this day.