Genesis 19:32-35

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. 34The next day, the firstborn said to the younger, “Behold, I lay last night with my father. Let us make him drink wine tonight also. Then you go in and lie with him, that we may preserve offspring from our father.” 35So 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.