Genesis 26:23-25

From there Isaac moved to Beersheba, where the LORD appeared to him on the night of his arrival. “I am the God of your father, Abraham,” he said. “Do not be afraid, for I am with you and will bless you. I will multiply your descendants, and they will become a great nation. I will do this because of my promise to Abraham, my servant.” Then Isaac built an altar there and worshiped the LORD. He set up his camp at that place, and his servants dug another well.