Genesis 21:27

“And Abraham took sheep and oxen, and gave them unto Abimelech, etc.] In gratitude for former favours he had received from him, in token of the friendship that subsisted between them, and for the confirmation of it; and to show that he was fully satisfied with Abimelech’s answer to his complaint, as well as willing to enter into covenant by sacrifice, when such creatures were divided, and the covenanters passed between the pieces, for so it follows: and both of them made a covenant; or, “cut or struck a covenant” f1239; cut the sacrifice in pieces and passed between them, in token of the compact and agreement they entered into with each other; signifying that whoever broke it deserved to be…”

“21:27-31 Abraham’s gifts to Abimelech (cp. 20:14) secured his legal right to dwell peaceably in the land and to claim ownership of the well. Beersheba marked one more step toward the fulfillment of God’s promise.”