Genesis 21:27-34
21:27 Abraham took some sheep and cattle and gave them to Abimelech. The two of them made a treaty.
21:28 Then Abraham set seven ewe lambs apart from the flock by themselves.
21:29 Abimelech asked Abraham, “What is the meaning of these seven ewe lambs that you have set apart?”
21:30 He replied, “You must take these seven ewe lambs from my hand as legal proof that I dug this well.”
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.