True delight in the Law of the Lord will produce hearts of repentance. We see this clearly in David’s response to God’s Law in Psalm 19. God’s revelation reveals to us our incompatibility as sinners with the holiness of God and the way he designed his creation to operate for his glory. Scripture explicitly teaches us that the payment for sin is death; it reproves and corrects us. As David says in Psalm 19:11, God’s Law warns us. It explicitly teaches us that “if we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness” (1 Jn 1:9). And so that is exactly what David does: he confesses his sin:
12 Who can understand his errors?
Cleanse me from secret faults.
13 Keep back your servant also from presumptuous sins;
let them not have dominion over me.
Then I shall be blameless,
and I shall be innocent of great transgression. (Ps 19:12–13)
Have Mercy on Me
Church tradition has identified seven psalms as “penitential psalms” (6, 32, 38, 51, 102, 130, 143), but several others also include themes of sorrow over sin, including 25, 39, 40, and 41.
There is perhaps a no more well-known confession of sin in all the psalms than Psalm 51. Book II of the Psalms is all about the extension of David’s rule over the nations. We remember stories of David’s exploits against the Philistines and all of the pagan nations surrounding Israel. “Saul has slain his thousands, but David his ten thousands!” But on one of those occasions, David didn’t go to battle with his soldiers like he normally did. Instead, he stayed back in his palace and committed a terrible sin of immorality with Bathsheba. And to make things worse, he then arranged for the death of Bathsheba’s husband so he could have her all for himself.
But as Psalm 19 makes clear, when God’s Word confronted David’s sin, David cleansed his heart through confession of sin. When the prophet Nathan, the mediator of God’s Word, confronted David’s sin—“You are the man!”—This man after God’s own heart immediately repented of his sin. David’s sin was in direct opposition to delighting in God’s Word. This is exactly what Nathan said: “Why have you despised the word of the Lord, to do what is evil in his sight?” Confronted with God’s Word, David replied, “I have sinned against the Lord.” He cleansed his heart through confession of sin. Look at David’s heart of confession in Psalm 51.
1 Have mercy upon me, O God,
according to your lovingkindness;
according to the multitude of your tender mercies,
blot out my transgressions.
2 Wash me thoroughly from my iniquity,
and cleanse me from my sin.
3 For I acknowledge my transgressions,
and my sin is always before me.
4 Against you, you only, have I sinned,
and done this evil in your sight—
that you may be found just when you speak,
and blameless when you judge. (Ps 51:1–4)
Because David delighted in God’s Word, he knew that a just God punishes sin. David also knew that forgiveness was possible, because he knew God’s character through his Word. He knew God would be merciful to him because of his steadfast love. David knew God would blot out his transgressions according to his abundant mercy. He knew that God is just and blameless, he knew that God delights in truth in the inward being, he knew the God would not despise a broken and contrite heart. David knew that God would cleanse his heart. And so he prays,
10 Create in me a clean heart, O God,
and renew a steadfast spirit within me.
11 Do not cast me away from your presence,
and do not take your Holy Spirit from me.
12 Restore to me the joy of your salvation,
and uphold me by your generous Spirit. (Ps 51:10–12)