Genesis 21:14, 31, 33

So Abraham rose early in the morning, and took bread and a skin of water; and putting it on her shoulder, he gave it and the boy to Hagar, and sent her away. Then she departed and wandered in the Wilderness of Beersheba.

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

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