1 Samuel 20:16-17, 42

So Jonathan made an agreement with David. He said, “May the LORD hold David’s enemies responsible.” And Jonathan asked David to repeat his promise of love for him, because he loved David as much as he loved himself.

Jonathan said to David, “Go in peace. We have promised by the LORD that we will be friends. We said, ‘The LORD will be a witness between you and me, and between our descendants always.’ ” Then David left, and Jonathan went back to town.