Synopsis of the Books of the Bible, by John Nelson Darby, [1857-62], at sacred-texts.com
2 Kings (2 Samuel) Chapter 21
And, first of all, the government of God, who forgets nothing, and with whom everything has its results, is recalled to David and to his people by means of the Gibeonites. It is no longer necessary for the establishment of God's economy that David should pursue the house of Saul. There is a righteous judgment, a moral principle of God, which is above all economies. Saul in his formal and fleshly zeal, although it was for God, had not acted in the fear of God. It is this which especially distinguishes a godly zeal from a zeal for the outward interests of His kingdom. Saul forgets the oaths which Israel made to the Gibeonites. God remembers it, and does not despise the poor Gibeonites. David also recognises its obligation; after having inquired of Jehovah on account of the thrice repeated chastening upon Israel, he submits to the demand of the Gibeonites [See Note #1]. The whole house of Saul perishes, except the little remnant attached to David. With respect to the latter, the circumstances of Rizpah's touching and faithful affection awaken in David's heart the remembrance of brighter moments in poor Saul's career, and he pays the last honours to his memory. After this God was entreated for the land.
If with a sling and a stone faith can overthrow its enemies, the flesh is at fault before their attacks. David, when king, as we have clearly seen, gave himself up more to his lusts and to his own will than David suffering. Nevertheless it is beautiful to see that, where faith has acted amid the people's ruin, it has stirred up many other instruments, who-animated and encouraged by its success-act fearlessly with the same power as that which wrought the first deliverance. It is well however to observe, that to conquer valiant foes, when all Israel was flushed with success and strengthened the hands of the mighty men, is a very different thing from the faith which reckons upon God, when strength and success are on the enemy's side and the people are fleeing before him. The latter was David's case with Goliath; the former, that of the men who slew the other giants.
Note #1
However, in yielding to the Gibeonites, David did not consult Jehovah as to what he should do. We see the government of God as to Saul's house, and Saul's act towards those he had wronged; but though in its general character righteous and upright, had he consulted Jehovah, some happier way of being righteous might have been found.