The king spared Mephibosheth; for the Gibeonites desiring only such a number, without designing the persons, it was at David's choice whom to spare. Or, he prevailed with the Gibeonites that they did not demand him; and with the Lord, that he might not be one of those who were devoted to destruction. The son of Jonathan: this is expressly added, to distinguish him from the other Mephibosheth, 2 Samuel 21:8.
Related Commentaries of 2 Samuel 21:7
2 Samuel 21:7
7 But the king spared Mephibosheth, the son of Jonathan the son of Saul, because of the LORD'S oath that was between them, between David and Jonathan the son of Saul.