Genesis 21:31-34

21:31 That is why he named that place Beer Sheba, because the two of them swore an oath there.

21:32 So they made a treaty at Beer Sheba. Then Abimelech and Phicol, the commander of his army, returned to the land of the Philistines. 21:33 Abraham planted a tamarisk tree in Beer Sheba. There he worshiped the Lord, the eternal God. 21:34 So Abraham stayed in the land of the Philistines for quite some time.