Psalm 18:20-24 — The Lord rewarded me according to my righteousness; according to the cleanness of my hands hath he recompensed me. For I have kept the ways of the Lord, and have not wickedly departed from my God. For all his judgments were before me, and I did not put away his statutes from me. I was also upright before him, and I kept myself from mine iniquity. Therefore hath the Lord recompensed me according to my righteousness, according to the cleanness of my hands in his eyesight.

I have always found this passage in Psalm 18 astounding. Could you make the claims David makes here? Be honest now … could you look at yourself in the mirror, read those words, and not blush? I couldn’t.
Now don’t get me wrong … I’m not a villain … in fact I like to think that by any human terms I’m not really a bad guy at all. But i’ve certainly done some things in my life that I’m ashamed of and I’m well aware, day to day, that I do things I shouldn’t and think thoughts that were better unthought.
But never mind my self-centered point of view. How about David? Was he really as clean-handed as he painted himself? In fact if you read his story you’ll find some pretty dubious activities, even before the shameful business with Uriah the Hittites wife. David himself seems to paint a very different story in the so-called “Penitential Psalms” — 6, 32, 38, 51, 102, 130 and 143. How are we to reconcile the two stories?
There is a deeper issue than the one of behavior. God’s view of David … and you, and me … is not based on behavior. His view is based on the heart. David knew that, no matter how his foot might slip from time, his integrity was sure. Spurgeon puts the case when he reflects on verse 21 in “The Treasury of David”:

The words of this verse refer to the saint as a traveller carefully keeping to “the ways of the Lord,” and “not wickedly,” that is, designedly, wilfully, persistently, defiantly forsaking the ordained pathway in which God favours the pilgrim with his presence. Observe how it is implied in the expression “and have not wickedly departed from my God,” that David lived habitually in communion with God, and knew him to be his own God, whom he might speak of as “my God.” God never departs from his people, let them take heed of departing from him.

Living our lives as best we can there is no inconsistency in honestly confessing and repenting our faults as David did, and asserting our integrity as David did — especially if we consider the context of David’s claim.
David is making no grand universal claim to perfection. Written at the start of this Psalm we find:

To the choirmaster. A Psalm of David, the servant of the LORD, who addressed the words of this song to the LORD on the day when the LORD rescued him from the hand of all his enemies, and from the hand of Saul.

David is claiming that as Saul unjustly attacked him, he had not responded wickedly. We know it is true, and that he did not raise his hand — ever — against the Lord’s anointed. His claim is that The Lord has blessed him for his obedience. When we show similar obedience, and when it is against a background of integrity, we may similarly anticipate that blessing!