Genesis 19:30-38

³⁰Lot went up from Zoar, and stayed in the mountains, and his two daughters with him; for he was afraid to stay in Zoar; and he stayed in a cave, he and his two daughters. ³¹Then 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 the earth. ³²Come, let us make our father drink wine, and let us lie with him that we may preserve our 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 our 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. ³⁷The firstborn bore a son, and called his name Moab; he is the father of the Moabites to this day. ³⁸As for the younger, she also bore a son, and called his name Ben-ammi; he is the father of the sons of Ammon to this day.