The king spared Mephibosheth. He was the son of Jonathan and the grandson of Saul. David had made a promise in front of the Lord. He had promised to be kind to Jonathan and the family line of his father Saul.
Jonathan said to David, “Go in peace. In the name of the Lord we’ve promised to be friends. We have said, ‘The Lord is a witness between you and me. He’s a witness between your children and my children forever.’ ” Then David left, and Jonathan went back to the town.
Now make a promise in the name of the Lord. Promise me that you won’t kill the children of my family. Also promise me that you won’t wipe out my name from my family line.”