Genesis 19:33-35

They got their father drunk with wine that very night. The older daughter went and lay with him. He was oblivious, knowing nothing of what she did. The next morning the older said to the younger, “Last night I slept with my father. Tonight, it’s your turn. We’ll get him drunk again and then you sleep with him. We’ll both get a child through our father and keep our family alive.” So that night they got their father drunk again and the younger went in and slept with him. Again he was oblivious, knowing nothing of what she did.