Genesis 21:14, 31, 33

Abraham rose up early the next morning, bundled up some food and a skin of water, and strapped them to Hagar’s shoulders. Then he gave her his son and sent them away. So, Hagar and her son Ishmael departed and wandered off into the wilderness of Beersheba.

That place was called Beersheba, because it was there that both men swore an oath to one another.

Abraham planted a tamarisk tree in Beersheba, and there he worshiped YAHWEH, the everlasting God.