Genesis 18:27, 30-32

Abraham answered, “Now behold, I who am but dust [in origin] and ashes have decided to speak to the Lord. [Gen 3:19; Job 30:19]

Then Abraham said [to Him], “Oh, may the Lord not be angry, and I will speak; suppose thirty [righteous people] are found there?” And He said, “I will not do it if I find thirty there.” And he said, “Now behold, I have decided to speak to the Lord [again]. Suppose [only] twenty [righteous people] are found there?” And the Lord said, “I will not destroy it for the sake of the twenty.” Then Abraham said, “Oh may the Lord not be angry [with me], and I will speak only this once; suppose ten [righteous people] are found there?” And He said, “I will not destroy it for the sake of the ten.”