Genesis 19:34 (KJV)

And it came to pass, when God destroyed the cities of the plain, that God remembered Abraham, and sent Lot out of the midst of the overthrow, when he overthrew the cities in the which Lot dwelt.

And Lot went up out of Zoar, and dwelt in the mountain, and his two daughters with him; for he feared to dwell in Zoar: and he dwelt in a cave, he and his two daughters.

And the firstborn said unto the younger, Our father is old, and there is not a man in the earth to come in unto us after the manner of all the earth:

Come, let us make our father drink wine, and we will lie with him, that we may preserve seed of our father.

And they made their father drink wine that night: and the firstborn went in, and lay with her father; and he perceived not when she lay down, nor when she arose.

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.

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

And the first born bare a son, and called his name Moab: the same is the father of the Moabites unto this day.

And the younger, she also bare a son, and called his name Benammi: the same is the father of the children of Ammon unto this day.