Genesis 19:34-38

34And it came to pass on the next day, that the firstborn said to the younger, Behold, I lay last night with my father: let us make him drink wine this night also; and go thou in, and lie with him, that we may preserve seed of our father. 35And they made their father drink wine that night also: and the younger arose, and lay with him; and he perceived not when she lay down, nor when she arose. 36Thus were both the daughters of Lot with child by their father. 37And the firstborn bore a son, and called his name Moab: the same is the father of the Moabites to this day. 38And the younger, she also bore a son, and called his name Benammi: the same is the father of the children of Ammon to this day.