Rashi on Genesis 18:17/רש"י על בראשית י״ח:י״ז

1המכסה אני SHALL I HIDE? This is a question.

2אשר אני עושה WHAT I AM DOING in Sodom. It is not proper for Me to do this thing without his knowledge. I gave him this land and these five cities therefore are his — as it is said, (10:19) “And the territory of the Canaanites was from Sidon … as thou goest towards Sodom and Gommorah etc.” I called him Abraham, the father of a multitude of nations; should I destroy the children without informing the father who loves me? (Genesis Rabbah 49:2)