Rashi on Genesis 20:1/רש"י על בראשית כ׳:א׳

1ויסע משם אברהם AND ABRAHAM JOURNEYED FROM THENCE—When he observed that the cities had been destroyed and travellers ceased to pass to and fro, he went away from there. Another explanation is: he journeyed from there to get away from Lot who had gained an evil reputation because of his intercourse with his daughters (Genesis Rabbah 52:3-4).