Psalm 51 shows what king David prayed when confronted with his sin of committing adultery with Bathsheba and plotting the death of Uriah the Hittite in battle to cover up his sin (2 Sam 11). The prophet Nathan told David that God had taken away his sin and that he wouldn't die (2 Sam 12:13b), but that what he had done would have serious consequences (2 Sam 12:1–23).
(For some Bible translations, two has to be added to the verses below in Psalm 51).
David knows that God's heart is a heart of mercy (Micah 7:18, Psalm 78:38,
86:5, 15), see God's Attributes. He also knows that he is guilty (2 Sam 12:13a,
Psalm 51:3). He admits that he has committed a heinous crime; a capital crime
(Psalm 51:14). There is no burnt offering for a capital offence (Psalm 51:16).
David therefore asks God to have mercy on him according to his steadfast love, and to blot out his transgressions according to God's abundant mercy (Psalm 51:1, 9).
Mercy means compassion and forgiveness towards someone whom it's within one's power to punish or harm. In the same way, we as Christians can and should cry out to God for mercy if and when we make mistakes and sin, see Sanctification.
David writes: "The sacrifices of God are a broken spirit; a broken and contrite heart,
O God, you will not despise." (Psalm 51:17), see 1) Blessed are the poor in spirit
in The Sermon on the Mount. David is poor in spirit (Psalm 86:1). This is the key to understanding why David is so blessed by God (Psalm 89:3–4, 19–37 (4–5, 20–38 in some translations), 132:11–12). Messiah would come from the lineage of David
(Acts 2:29–31, 2 Sam 7:12–13).
David asks God to make him spiritually and morally clean (Psalm 51:2). He feels himself to be spiritually and morally filthy. He sees himself as a spiritual leper because of what he has done (Psalm 51:7, Lev 14:6–7a). David needs a new heart and a steadfast spirit (Psalm 51:10). He needs it to resist the temptation of sin.
David wants God to strengthen him to better resist the sin in his life (Psalm 51:12b).
He needs the wisdom that comes from God (Psalm 51:6). David also wants to hear joy and gladness after all mourning (Psalm 51:8, 12a).
Then he would teach transgressors God's ways, so that sinners would return to God (Psalm 51:13). David is already looking beyond the situation to see how the Lord would use it in his life to help other people. Our experience of failure gives us
a unique voice that speaks into the hearts of other people going through similar situations.
David says he has sinned against the Lord, and him alone (Psalm 51:4).
He acknowledges that God is the ultimate judge of all. At the end of it all,
it's God and God alone he will stand before. The final judgement is always God and David knows that. He doesn't minimize the sin he has committed against
Bathsheba and Uriah the Hittite. David makes no excuses for his sin.
He makes a theological declaration that he was born in iniquity, and in sin his mother conceived him (Psalm 51:5). Sin came into the world through Adam and death through sin, and so death spread to all men because all sinned (Rom 5:12–14,
Gen 2:16–17, 3:3, 17–19), see The Biblical Creation and the Fall of Man.
He asks God to not throw him away from God's presence and not to take the
Holy Spirit from him (Psalm 51:11). This was something that happened to Saul.
The Holy Spirit didn't live inside people at that time. In the Old Testament,
the Holy Spirit lived with and upon them, see Jesus the Light of the World.
David understands that there is a connection between his personal holiness as
king and leader and God's blessings for the nation of Israel (Psalm 51:18–19).
He represents the people of Israel before God. Character counts. This is important for every Christian leader to understand, see The Book of Timothy.
Psalm 51 is called David's prayer for repentance, but is also David's prayer for brokenness from pride, to be compared with the last part of The Apostle Peter,
who needed to be broken from pride in order to act as leader among God's children.
See also The Book of Psalms.
