Synopsis of the Books of the Bible, by John Nelson Darby, [1857-62], at sacred-texts.com
The following commentary covers Chapters 29 and 30.
In chapter 29 God, in His loving-kindness, brings David out of his difficulty by means of the jealousy of the lords of the Philistines. Nevertheless, to maintain his credit with Achish, David falls still lower, it seems to me, and protests that he is quite ready to fight against the enemies of the Philistine king, that is to say, against the people of God. This appears to me the most wretched part of David's life-at any rate, before he was king. God makes him sensible of it; for while he is there, the Amalekites strip him of everything and burn Ziklag, and his followers are ready to stone him. All this is grievous; but the grace of God raises him up again, and the effect of this chastisement is to bring him back to God, for he was ever true to Him in heart. David encouraged himself in Jehovah his God, and inquires of Him what he shall do. What patience, what kindness in God! What care He takes of His people, even while they are turning away from Him!
David is truly brought back to God, and rescued from his false position, and he walks and acts with God. God was, unknown to him, preparing a very different position for him, and was purifying and preparing him for it. How dreadful would it have been, had David been with the Philistines, and taken part in the defeat of God's people, and in the death of him whose life he had often spared so touchingly! How far the child of God may go astray when he puts himself under the protection of unbelievers, instead of relying on the help of God in all the difficulties which beset the path of faith! It is through these very difficulties that every grace is developed. And observe the danger the believer is in-if his faith be not simple, but fails ever so little-of being thrown into the arms of God's enemies through the persecution of professors. Nature grows weary, and seeks comfort afar from the narrow path which leads through the briars. This happens whenever the people of God, following their own will, confide their interests to those who seek nothing but their own advantage in a less difficult position, which is neither that of God nor that of faith. And the more glorious a work there is for faith, the more nature grows weary, if faith becomes weak. Ziklag is taken during David's absence, but he pursues the spoilers, and recovers all the booty. David, upright and generous, found, in the difficulty which arose from the selfishness of his people, an opportunity to institute that which was conformable to the will of God; and instead of seeking to enrich himself through his share of the spoil, he uses it to maintain kindly relations with the elders of his people, and to prove to them that Jehovah is still with him.