Genesis 19:29-33
English Standard Version
30Now Lot went up out of Zoar and lived in the hills with his two daughters, for he was afraid to live in Zoar. So he lived in a cave with his two daughters.
31And the firstborn said to the younger, "Our father is old, and there is not a man on earth to come in to us after the manner of all the earth.
32Come, let us make our father drink wine, and we will lie with him, that we may preserve offspring from our father."
33So they made their father drink wine that night. And the firstborn went in and lay with her father. He did not know when she lay down or when she arose.