Rashi on Genesis 19:29/רש"י על בראשית י״ט:כ״ט

1ויזכר אלהים את אברהם GOD REMEMBERED ABRAHAM — What bearing has God’s remembering Abraham upon the rescue of Lot? He remembered that Lot knew that Sarah was Abraham’s wife and that when he heard that Abraham said in Egypt regarding Sarah, “She is my sister”, he did not betray him because he had sympathy with him. For this reason God had mercy upon him (Lot) (Genesis Rabbah 51:6).