Genesis 21:27
And Abraham took sheep and oxen, and gave them unto Abimelech; and both of them made a covenant.
Cross-references
Genesis 21:32 continues the same covenant event — after the treaty is made at Beersheba, Abimelech and his commander depart.
Genesis 26:28-31 records a similar covenant between Isaac and Abimelech, showing continuity of peace agreements.
Genesis 31:44 describes Jacob and Laban making a covenant, another formal agreement similar to Abraham's.
Genesis 14:23 has Abraham refusing to take anything from the king of Sodom. Here he gives livestock to seal a treaty — contrasting motivations around material goods in Abraham's dealings with foreign kings.
Proverbs 18:16 states gifts open access to the great, echoing how Abraham's gifts facilitated covenant with King Abimelech.
Galatians 3:15 uses the principle that a ratified human covenant cannot be altered — much like this covenant between Abraham and Abimelech that stands as settled agreement.