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, Co2 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 (Psa 18:20, Psa 18:24), 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, Psa 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 (Psa 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, Ti1 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, Psa 18:25, Psa 18:26. 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, Mat 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, Lev 26:24.

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.

I was also upright before him,.... In heart and conversation, being sincere and faithful; so David was in the sight of God; but this is much more true of Christ, in whom there was no unrighteousness nor guile, neither in his heart, nor in his lips; he was of perfect integrity, and faithful in all things to him that appointed him;

and I kept myself from mine iniquity; which some interpret of original sin, in which David was born, which dwelt in him, and prompted him to sin; but rather it refers to the taking away of Saul's life, which he might be tempted to do, as being his enemy that sought his life; and which he was put upon and urged to by some about him, and yet did it not. But it is best here also to apply these words to Christ; for though he had no iniquity of his own, yet he had the iniquities of his people on him, as their surety, and which he calls "mine", Psa 40:12. But though he bore them, he did not commit any of them; though he was made sin, he knew none; and though he was tempted by Satan to the most enormous iniquities, as destroying himself and worshipping the devil, he kept himself from the evil one, that he could not touch him: the sense is, that he kept himself from committing any sin, which cannot be said of any mere man; and so far as good men are kept from sin, they are kept by the power of God, and not by themselves. All these things show, that the righteousness of Christ was a perfect, sinless one, entirely agreeable to the laws, statutes, and judgments of God; was pure in the sight of God, and rewardable in strict justice. Hence it is repeated as follows:

The statements of innocence, righteousness, &c., refer, doubtless, to his personal and official conduct and his purposes, during all the trials to which he was subjected in Saul's persecutions and Absalom's rebellions, as well as the various wars in which he had been engaged as the head and defender of God's Church and people.