Genesis 21:25-31

Then Abraham rebuked Abimelech because of a well of water which Abimelech’s servants had seized. And Abimelech said, “I do not know who has done this thing; you did not tell me, nor had I heard of it until today.” So Abraham took sheep and oxen and gave them to Abimelech, and the two of them made a covenant. And Abraham set seven ewe lambs of the flock by themselves. Then Abimelech asked Abraham, “What is the meaning of these seven ewe lambs which you have set by themselves?” And he said, “You will take these seven ewe lambs from my hand, that they may be my witness that I have dug this well.” Therefore he called that place Beersheba, because the two of them swore an oath there.