Genesis 21:29-33

Then Abimelech said to Abraham, “What do these seven ewe lambs mean, which you have set by themselves?”

He said, “You shall take these seven ewe lambs from my hand so that it may be a witness for me, that I dug this well.”

Therefore he called that place Beersheba, because there the two of them took an oath.

So they made a covenant at Beersheba; and Abimelech and Phicol, the commander of his army, got up and returned to the land of the Philistines.

Abraham planted a tamarisk tree at Beersheba, and there he called on the name of the Lord, the Everlasting God.