The king had mercy on Mephibosheth son of Jonathan, the son of Saul, in light of the Lord's oath that had been taken between David and Jonathan son of Saul.

Then David asked, "Is anyone still left from the family of Saul, so that I may extend kindness to him for the sake of Jonathan?" Now there was a servant from Saul's house named Ziba, so he was summoned to David. The king asked him, "Are you Ziba?" He replied, "At your service." The king asked, "Is there not someone left from Saul's family, that I may extend God's kindness to him?" Ziba said to the king, "One of Jonathan's sons is left; both of his feet are crippled." read more.
The king asked him, "Where is he?" Ziba told the king, "He is at the house of Makir son of Ammiel in Lo Debar. So King David had him brought from the house of Makir son of Ammiel in Lo Debar. When Mephibosheth son of Jonathan, the son of Saul, came to David, he bowed low with his face toward the ground. David said, "Mephibosheth?" He replied, "Yes, at your service." David said to him, "Don't be afraid, because I will certainly extend kindness to you for the sake of Jonathan your father. You will be a regular guest at my table."