Genesis 19:31-36

31Then the firstborn said to the younger, “Our father is old, and there is not a man 1on earth to 2come in to us after the manner of the earth.

32Come, 3let us make our father drink wine, and let us lie with him that we may preserve 4our family through our father.”

33So 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.

34On the following 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 5our family through 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.

36Thus both the daughters of Lot were with child by their father.