“The title of this psalm gives the tragic context for David’s plea. He had sinned in murder, in adultery, in covering his sin, and in hardness against repentance. It took the bold confrontation of Nathan the Prophet to shake him from this (2 Samuel 12); yet once shaken, David came in great honesty and brokenness before God.  –David Guzik
 A Prayer of Repentance (Psalm 51)
To the Chief Musician. A Psalm of David when Nathan the prophet went to him, after he had gone in to Bathsheba.
1 Have mercy upon me, O God, According to Your lovingkindness;  According to the multitude of Your tender mercies, Blot out my transgressions.

David approached God in complete humility.  He didn’t attempt to justify his sins, he simply presented himself to God as a sinner in need of a savior.  David begins the psalm with the words “Have mercy upon me, O God, According to Your lovingkindness”.  David offers no defense for himself… he asks to be judged according to God’s lovingkindness, or God’s covenant mercy.  David’s words convey his complete brokenness.
David used several words to speak of his offense against God.

Transgressions has the idea of crossing a boundary.

Iniquity has the idea of twistedness or perversion.

Sin has the idea of falling short or missing the mark.

2 Wash me thoroughly from my iniquity, And cleanse me from my sin.

In verse 2…the phrase “Wash me thoroughly” has the idea of repeatedly washing by kneading or beating, not a simple rinsing.  Trapp commented:  “To be cleansed not only from outward defilements, but from his swinish nature; for though a swine be washed never so clean, if she retain her nature, she will be ready to wallow in the next guzzle.”

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.

David was unable to escape his sins (plural).  Despite his attempts to ignore and deny his sins, David had been unable to move past them.  His conscience constantly pointed to the unconfessed sins that he attempted to leave in the past.  David was the king of Israel with all of the riches and power that came with the title.  However, before God, he was no different than the lowest servant in the kingdom… unable to atone for his own sins.

5 Behold, I was brought forth in iniquity, And in sin my mother conceived me.  6 Behold, You desire truth in the inward parts, And in the hidden part You will make me to know wisdom.

In these verses, David is acknowledging the biblical idea of “original sin” – the idea that all humans are born sinners, receiving a sinful nature as children of Adam and Eve.  David didn’t make a conscience decision one day that he would go out and sin.  The sin was a result of his sinful nature that was present at birth.
David is not saying this in order to deflect blame or make excuses for his failures.  Quite the opposite, David is acknowledging the need for God to do a work “in the inward parts” of his being and bring wisdom to his “hidden parts”.  Instead of making excuses for his sins, David is acknowledging his need for God to perform a thorough work deep within him.  He was calling on God to do what he could not do for himself.

7 Purge me with hyssop, and I shall be clean; Wash me, and I shall be whiter than snow.  8 Make me hear joy and gladness, That the bones You have broken may rejoice.  9 Hide Your face from my sins, And blot out all my iniquities.

Hyssop was used to apply the blood of the Passover lamb to the lintel and doorposts…. (Exodus 12:22-23) And you shall take a bunch of hyssop, dip it in the blood that is in the basin, and strike the lintel and the two doorposts with the blood that is in the basin. And none of you shall go out of the door of his house until morning.  For the LORD will pass through to strike the Egyptians; and when He sees the blood on the lintel and on the two doorposts, the LORD will pass over the door and not allow the destroyer to come into your houses to strike you.
Hyssop was also used to sprinkle water on an unclean person… (Numbers 19:18) A clean person shall take hyssop and dip it in the water, sprinkle it on the tent, on all the vessels, on the persons who were there, or on the one who touched a bone, the slain, the dead, or a grave.  The clean person shall sprinkle the unclean on the third day and on the seventh day; and on the seventh day he shall purify himself, wash his clothes, and bathe in water; and at evening he shall be clean.
In this psalm, David repeatedly acknowledges his sin and asks (even begs) for God to cleanse him.  This was not a light thing for David.  Only through a true working of God can David again experience the joy and gladness of restoration in his relationship with God.

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.

-Regarding the word “Create”, Boice comments: “The word that begins this section is the Hebrew verb bara, which is used in Genesis 1 for the creation of the heavens and the earth by God. Strictly used, this word describes what only God can do: create ex nihilo, out of nothing.”
The idea that David is conveying is that his heart is so corrupt, so broken, that it needs to be replaced anew… simply “fixing” it is not sufficient.  David associates having a “clean heart” with a “steadfast spirit”.  The desire for a “clean heart” and a “steadfast spirit” is David’s desire for a close relationship with God.
Horne comments: “The soul that is truly penitent, dreads nothing but the thought of being rejected from the ‘presence,’ and deserted by the ‘Spirit’ of God. This is the most deplorable and irremediable effect of sin; but it is one that in general, perhaps, is the least considered and regarded of all others.”

12 Restore to me the joy of Your salvation, And uphold me by Your generous Spirit.  13 Then I will teach transgressors Your ways, And sinners shall be converted to You.

David has suffered in his unconfessed sin for many months.  The separation from God was unbearable for him.  He wanted to experience “the joy of Your Salvation”… or being rescued from his sins.  David realizes that only God can rescue him from his sins and restore him.  Here he is placing his faith in God alone for this restoration.
Living in this sin has had a crippling effect on David’s ability to serve God.  Only through being restored can David again represent God to those around him.  Our service to God is a function of God working through us.  When we serve God, we are allowing God to guide and direct us to accomplish his will.  We are His ambassadors.  When the relationship is damaged (such as separation through our sins), our ability to serve God is hindered (if not completely broken).  David has a long history of faithful service to God, beginning as a young boy.  The distance between David and God (as a result of his sins) has crippled the ability for David to serve God.  Through his restoration, David will again be in a place where God can use him to teach others.

14 Deliver me from the guilt of bloodshed, O God, The God of my salvation, And my tongue shall sing aloud of Your righteousness.  15 O Lord, open my lips, And my mouth shall show forth Your praise.  16 For You do not desire sacrifice, or else I would give it; You do not delight in burnt offering.  17 The sacrifices of God are a broken spirit, A broken and a contrite heart— These, O God, You will not despise.

David has been a part of many animal sacrifices over his years.  In fact, he likely has continued offering animal sacrifices on the altar over the past several months only to realize that these sacrifices have little ability to atone for unconfessed sins.  Only through confessing his sins and his present condition… having a broken spirit and a broken and contrite heart… can David petition God to cleanse him of his sins and begin to restore the relationship between them.
David recognizes the value that God places on a broken spirit and a broken and contrite heart.  These represent fertile ground that God can cultivate.  Here, God can establish a relationship.  David looks forward to this.  He desires for God to begin the work in him again that will allow him to sing God’s praises once again.

18 Do good in Your good pleasure to Zion; Build the walls of Jerusalem.  19 Then You shall be pleased with the sacrifices of righteousness, With burnt offering and whole burnt offering; Then they shall offer bulls on Your altar.

David recognized that he had not only sinned as a man, but he had also sinned as a king over God’s people.  David had been appointed and entrusted to lead and care for the people of the nation of Israel.  His sins directly impacted the lives of those under his charge.  David knew this was something that God did not take lightly.
David petitions God to restore His “good pleasure” with Israel.  Still under the Old Covenant, the animal sacrifices were an important part of the relationship between God and His people.  David demonstrates that he still valued the condition of the people under his charge.  He wanted to restore God’s favor with them that their sacrifices at the altar could be received by God with great pleasure.
David, as a warrior, knew the value of restoring the fractured relationship with God.  Upon recognizing the unconfessed sins and the damage they had caused… he approached God in prayer.  This was not optional for David and is not optional for us when we sin against God.  The sin must be addressed and the relationship restored before the service to God can continue.

“This great song, pulsating with the agony of a sin-stricken soul, helps us to understand the stupendous wonder of the everlasting mercy of our God.”  – G. Campbell Morgan
May you quickly acknowledge and humbly confess your sins to your God and your Savior so that your relationship will remain strong and you will be filled to overflowing with His grace and mercy.
God bless,