Genesis 26:26-31

Then Abimelech came to him from Gerar with Ahuzzath, his [close friend and confidential] adviser, and Phicol, the commander of his army. Isaac said to them, “Why have you [people] come to me, since you hate me and have sent me away from you?” They said, “We see clearly that the LORD has been with you; so we said, ‘There should now be an oath between us [with a curse for the one who breaks it], that is, between you and us, and let us make a covenant (binding agreement, solemn promise) with you, that you will not harm us, just as we have not touched you and have done nothing but good to you and have sent you away in peace. You are now the blessed and favored of the LORD!’ ” Then Isaac held a [formal] banquet (covenant feast) for them, and they ate and drank. They got up early in the morning and swore oaths [pledging to do nothing but good to each other]; and Isaac sent them on their way and they left him in peace.