If there was no other passage in this Psalm to imply that David delivered this song of praise under the spirit of prophecy, in reference to the Lord Jesus Christ, than what these verses contain, what is here said would be enough to determine the point. For David, in no part of his life, ever could make use of such expressions. It would be straining the language too far, to suppose that he meant to say such things of himself, considered in his being kept from idolatry, and his attachment to the true God of Israel. Clean hands, free from sin, and no wicked departures from God, would even then be too strong expressions, consistent with the many sins of David's life. But reading these blessed truths in reference to Jesus, oh! what very delightful features do they give of him and his pure nature, who was holy, harmless, undefiled, separate from sinners, and made higher than the heavens. Hebrews 7:26. Neither is this all. For the recompense of this holiness and obedience of Jesus, we are interested in so very highly, that everyone would be very cautious how he parted with a single portion respecting Christ, his glorious Surety, to adorn David with what never could belong to him.
Related Commentaries of Psalms 18:20
Psalms 18:20-24
20 The LORD rewarded me according to my righteousness; according to the cleanness of my hands hath he recompensed me.
21 For I have kept the ways of the LORD, and have not wickedly departed from my God.
22 For all his judgments were before me, and I did not put away his statutes from me.
23 I was also upright before him, and I kept myself from mine iniquity.
24 Therefore hath the LORD recompensed me according to my righteousness, according to the cleanness of my hands in his eyesight.