Adam Clarke on Genesis 20:1

And Abraham journeyed - It is very likely that this holy man was so deeply affected with the melancholy prospect of the ruined cities, and not knowing what was become of his nephew Lot and his family, that he could no longer bear to dwell within sight of the place. Having, therefore, struck his tents, and sojourned for a short time at Kadesh and Shur, he fixed his habitation in Gerar, which was a city of Arabia Petraea, under a king of the Philistines called Abimelech, my father king, who appears to have been not only the father of his people, but also a righteous man.