Charles Ellicott Commentary Genesis 21:34

"And Abraham sojourned in the land of the Philistines many days." — Genesis 21:34 (ASV)

In the Philistines’ land —In Genesis 21:32, Abimelech, on returning to Gerar, is said to have gone back into the land of the Philistines. But Beer-sheba also, in a general way, belonged to his dominions, and Abraham dwelt there in peace because of the treaty which existed between him and the Philistine king.