Genesis 21:31-34

That’s how the place got named Beersheba (the Oath-Well), because the two of them swore a covenant oath there. After they had made the covenant at Beersheba, Abimelech and his commander, Phicol, left and went back to Philistine territory. Abraham planted a tamarisk tree in Beersheba and worshiped GOD there, praying to the Eternal God. Abraham lived in Philistine country for a long time. * * *