We see here the Kindness of God's King. David having been given victory over his enemies, rules his kingdom with justice and righteousness. He fulfils here his promises to Saul:

1 Samuel 24: 20 “Now I know for certain you will be king, and the kingdom of Israel will be established[j] in your hand. 21 Therefore swear to me by the Lord that you will not cut off my descendants or wipe out my name from my father’s family.” 22 So David swore to Saul. Then Saul went back home, and David and his men went up to the stronghold.

And his promise to Jonathan. 1Samuel 20:14 If I continue to live, show me kindness from the Lord, but if I die, 15 don’t ever withdraw your kindness from my household—not even when the Lord cuts off every one of David’s enemies from the face of the earth.” 

2 Samuel 9:1 David asked, “Is there anyone remaining from the family of Saul I can show kindness to for Jonathan’s sake?” 2 There was a servant of Saul’s family named Ziba. They summoned him to David, and the king said to him, “Are you Ziba?” “I am your servant,” he replied. 3 So the king asked, “Is there anyone left of Saul’s family that I can show the kindness of God to?” Ziba said to the king, “There is still Jonathan’s son who was injured in both feet.” 4 The king asked him, “Where is he?”

Ziba answered the king, “You’ll find him in Lo-debar at the house of Machir son of Ammiel.” 5 So King David had him brought from the house of Machir son of Ammiel in Lo-debar.

6 Mephibosheth son of Jonathan son of Saul came to David, fell facedown, and paid homage. David said, “Mephibosheth!”

“I am your servant,” he replied.

7 “Don’t be afraid,” David said to him, “since I intend to show you kindness for the sake of your father Jonathan. I will restore to you all your grandfather Saul’s fields, and you will always eat meals at my table.”