Or HaChaim on Genesis 18:26/אור החיים על בראשית י״ח:כ״ו

1 ויאמר ה׳ אם אמצא…ונשאחי לכל המקום. G'd said: "If I find fifty ….inside the town, I will forgive the whole place on their account." G'd answered only Abraham's last request. It goes without saying that He would not kill the innocent. We know that G'd saved Lot who was not righteous because he was a relative of Abraham.