Genesis 19:34-36

New King James Version

³⁴ It happened on the next day that the firstborn said to the younger, “Indeed I lay with my father last night; let us make him drink wine tonight also, and you go in and lie with him, that we may preserve the ^[a]lineage of our father.” ³⁵ Then 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.

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