7 But the king spared Mephibosheth, the son of Jonathan the son of Saul, because of Yahweh's oath that was between them, between David and Jonathan the son of Saul.
*Minor differences ignored. Grouped by changes, with first version listed as example.
The Lord's oath - The calamity brought upon Israel by Saul's breach of the oath to the Gibeonites would make David doubly careful in the matter of his own oath to Jonathan.
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.
Spared - For the Gibeonites desiring only such a number, it was at David's choice whom to spare. Of Jonathan - This is added, to distinguish him from the other Mephibosheth, 2-Samuel 21:8.
*More commentary available at chapter level.