Genesis 21:14, 31, 33

So Abraham rose early in the morning and took bread and a skin of water and gave them to Hagar, putting them on her shoulder, and gave her the boy, and sent her away. And she departed and wandered about in the wilderness of Beersheba.

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

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