Here, I. David reflects with comfort upon his own integrity, and rejoices in the testimony of his conscience that he had had his conversation in godly sincerity and not with fleshly wisdom, 2 Cor. 1:12. His deliverances were an evidence of this, and this was the great comfort of his deliverances. His enemies had misrepresented him, and perhaps, when his troubles continued long, he began to suspect himself; but, when God visibly took his part, he had both the credit and the comfort of his righteousness. 1. His deliverances cleared his innocency before men, and acquitted him from those crimes which he was falsely accused of. This he calls rewarding him according to his righteousness (Ps. 18:20, 24), that is, determining the controversy between him and his enemies, according to the justice of his cause and the cleanness of his hands, from that sedition, treason, and rebellion, with which he was charged. He had often appealed to God concerning his innocency; and now God had given judgment upon the appeal (as he always will) according to equity. 2. They confirmed the testimony of his own conscience for him, which he here reviews with a great deal of pleasure, Ps. 18:21-23. His own heart knows, and is ready to attest it, (1.) That he had kept firmly to his duty, and had not departed, not wickedly, not wilfully departed, from his God. Those that forsake the ways of the Lord do, in effect, depart from their God, and it is a wicked thing to do so. But though we are conscious to ourselves of many a stumble, and many a false step taken, yet if we recover ourselves by repentance, and go on in the way of our duty, it shall not be construed into a departure, for it is not a wicked departure, from our God. (2.) That he had kept his eye upon the rule of God’s commands (Ps. 18:22): “All his judgments were before me; and I had a respect to them all, despised none as little, disliked none as hard, but made it my care and business to conform to them all. His statutes I did not put away from me, out of my sight, out of my mind, but kept my eye always upon them, and did not as those who, because they would quit the ways of the Lord, desire not the knowledge of those ways.” (3.) That he had kept himself from his iniquity, and thereby had approved himself upright before God. Constant care to abstain from that sin, whatever it be, which most easily besets us, and to mortify the habit of it, will be a good evidence for us that we are upright before God. As David’s deliverances cleared his integrity, so did the exaltation of Christ clear his, and for ever roll away the reproach that was cast upon him; and therefore he is said to be justified in the Spirit, 1 Tim. 3:16.
II. He takes occasion thence to lay down the rules of God’s government and judgment, that we may know not only what God expects from us, but what we may expect from him, Ps. 18:25, 26. 1. Those that show mercy to others (even they need mercy, and cannot depend upon the merit, no, not of their works of mercy) shall find mercy with God, Matt. 5:7. 2. Those that are faithful to their covenants with God, and the relations wherein they stand to him, shall find him all that to them which he has promised to be. Wherever God finds an upright man, he will be found an upright God. 3. Those that serve God with a pure conscience shall find that the words of the Lord are pure words, very sure to be depended on and very sweet to be delight in. 4. Those that resist God, and walk contrary to him, shall find that he will resist them, and walk contrary to them, Lev. 26:21, 24.
III. Hence he speaks comfort to the humble (“Thou wilt save the afflicted people, that are wronged and bear it patiently”), terror to the proud (“Thou wilt bring down high looks, that aim high, and look with scorn and disdain upon the poor and pious”), and encouragement to himself—“Thou wilt light my candle, that is, thou wilt revive and comfort my sorrowful spirit, and not leave me melancholy; thou wilt recover me out of my troubles and restore me to peace and prosperity; thou wilt make my honour bright, which is now eclipsed; thou wilt guide my way, and make it plain before me, that I may avoid the snares laid for me; thou wilt light my candle to work by, and give me an opportunity of serving thee and the interests of thy kingdom among men.”
Let those that walk in darkness, and labour under many discouragements in singing these verses, encourage themselves that God himself will be a light to them.