Genesis 19:30-38

Then Lot went up out of Zoar and dwelt in the mountains, and his two daughters were with him; for he was afraid to dwell in Zoar. And he and his two daughters dwelt in a cave. Now the firstborn said to the younger, “Our father is old, and there is no man on the earth to come in to us as is the custom of all the earth. Come, let us make our father drink wine, and we will lie with him, that we may preserve the lineage of our father.” So they made their father drink wine that night. And the firstborn went in and lay with her father, and he did not know when she lay down or when she arose. It happened on the next day that the firstborn said to the younger, “Indeed I lay with my father last night; let us make him drink wine tonight also, and you go in and lie with him, that we may preserve the lineage of our father.” Then they made their father drink wine that night also. And the younger arose and lay with him, and he did not know when she lay down or when she arose. Thus both the daughters of Lot were with child by their father. The firstborn bore a son and called his name Moab; he is the father of the Moabites to this day. And the younger, she also bore a son and called his name Ben-Ammi; he is the father of the people of Ammon to this day.