New Defender's Study Bible Notes
21:31 Beer-sheba. “Beer-sheba” means both “well of the oath” and “well of the seven.” Even though it was on land claimed by the Philistines, it was commonly understood at the time that the man who dug a well was its owner.
21:33 everlasting God. This is the first time this particular name of God is used (“Jehovah, El Olam,” meaning “Jehovah is the eternal God”). Abraham realized that, though he had made a covenant with a temporal king, he was really the recipient of the covenant promises of an eternal king. He had granted Abimelech tentative possession of a portion of the promised land, but Jehovah’s covenant promised his own seed its eternal possession.
21:34 many days. As far as the record goes, Abraham had never returned from “sojourning” (note Genesis 21:23) in the land of the Philistines since the time he and Sarah had moved there before Isaac was born (Genesis 20:1) and Abimelech had granted him freedom to dwell anywhere in his land (Genesis 20:15).