2 Samuel 21:7

7 The king spared Mephibosheth son of Jonathan, the son of Saul, because of the promise David and Jonathan had spoken before God.

2 Samuel 21:7 Meaning and Commentary

2 Samuel 21:7

But the king spared Mephibosheth, the son of Jonathan, the son
of Saul
As they did not name particular persons, only required seven sons, it was at the option of the king what sons to deliver to them, and therefore kept back Mephibosheth, who is thus described, to distinguish him from a son of Saul's of the same name, after mentioned:

because of the Lord's oath that [was] between them, between David and
Jonathan the son of Saul;
not merely or only out of affection to Mephibosheth, but because of the oath, that he might not be guilty of the same crime Saul was in slaying the Gibeonites.

2 Samuel 21:7 In-Context

5 Then they told the king, "The man who tried to get rid of us, who schemed to wipe us off the map of Israel

6 - well, let seven of his sons be handed over to us to be executed - hanged before God at Gibeah of Saul, the holy mountain." And David agreed, "I'll hand them over to you."

7 The king spared Mephibosheth son of Jonathan, the son of Saul, because of the promise David and Jonathan had spoken before God.

8 But the king selected Armoni and Mephibosheth, the two sons that Rizpah daughter of Aiah had borne to Saul, plus the five sons that Saul's daughter Merab had borne to Adriel son of Barzillai the Meholathite.

9 He turned them over to the Gibeonites who hanged them on the mountain before God - all seven died together. Harvest was just getting underway, the beginning of the barley harvest, when they were executed.