Genesis 18:29

And Abraham answered and said, Behold now, I have taken upon me to speak unto the Lord, which [am but] dust and ashes:

Peradventure there shall lack five of the fifty righteous: wilt thou destroy all the city for [lack of] five? And he said, If I find there forty and five, I will not destroy [it].

And he said [unto him], Oh let not the Lord be angry, and I will speak: Peradventure there shall thirty be found there. And he said, I will not do [it], if I find thirty there.

And he said, Behold now, I have taken upon me to speak unto the Lord: Peradventure there shall be twenty found there. And he said, I will not destroy [it] for twenty's sake.