Genesis 19:34-36

BRG Bible

³⁴ And it came to pass on the morrow, that the firstborn said unto the younger, Behold, I lay yesternight with my father: let us make him drink wine this night also; and go thou in, and lie with him, that we may preserve seed of our father.

³⁵ And they made their father drink wine that night also: and the younger arose, and lay with him; and he perceived not when she lay down, nor when she arose.

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