Genesis 21:22-31

Now it came about at that time that Abimelech and Phicol, the commander of his army, spoke to Abraham, saying, “God is with you in all that you do; now therefore, swear to me here by God that you will not deal falsely with me or with my offspring or with my posterity, but according to the kindness that I have shown to you, you shall show to me and to the land in which you have sojourned.” Abraham said, “I swear it.” But Abraham complained to Abimelech because of the well of water which the servants of Abimelech had seized. And Abimelech said, “I do not know who has done this thing; you did not tell me, nor did I hear of it until today.” Abraham took sheep and oxen and gave them to Abimelech, and the two of them made a covenant. Then Abraham set seven ewe lambs of the flock by themselves. Abimelech said to Abraham, “What do these seven ewe lambs mean, which you have set by themselves?” He said, “You shall take these seven ewe lambs from my hand so that it may be a witness to me, that I dug this well.” Therefore he called that place Beersheba, because there the two of them took an oath.