Genesis 26:26-33

26Meanwhile, Abimelek had come to him from Gerar, with Ahuzzath his personal adviser and Phicol the commander of his forces.

27Isaac asked them, “Why have you come to me, since you were hostile to me and sent me away?” 28They answered, “We saw clearly that the LORD was with you; so we said, ‘There ought to be a sworn agreement between us’—between us and you. Let us make a treaty with you

29that you will do us no harm, just as we did not harm you but always treated you well and sent you away peacefully. And now you are blessed by the LORD .” 30Isaac then made a feast for them, and they ate and drank.

31Early the next morning the men swore an oath to each other. Then Isaac sent them on their way, and they went away peacefully. 32That day Isaac’s servants came and told him about the well they had dug. They said, “We’ve found water!”

33He called it Shibah, Shibah can mean oath or seven. and to this day the name of the town has been Beersheba. Beersheba can mean well of the oath and well of seven.