Psalms 51:2

David, being convinced of his sin, poured out his soul to God in prayer for mercy and grace. Whither should backsliding children return, but to the Lord their God, who alone can heal them? he drew up, by Divine teaching, an account of the workings of his heart toward God. Those that truly repent of their sins, will not be ashamed to own their repentance. Also, he instructs others what to do, and what to say. David had not only done much, but suffered much in the cause of God; yet he flees to God's infinite mercy, and depends upon that alone for pardon and peace. He begs the pardon of sin. The blood of Christ, sprinkled upon the conscience, blots out the transgression, and, having reconciled us to God, reconciles us to ourselves. The believer longs to have the whole debt of his sins blotted out, and every stain cleansed; he would be thoroughly washed from all his sins; but the hypocrite always has some secret reserve, and would have some favorite lust spared. David had such a deep sense of his sin, that he was continually thinking of it, with sorrow and shame. His sin was committed against God, whose truth we deny by wilful sin; with him we deal deceitfully. And the truly penitent will ever trace back the streams of actual sin to the fountain of original depravity. He confesses his original corruption. This is that foolishness which is bound in the heart of a child, that proneness to evil, and that backwardness to good, which is the burden of the regenerate, and the ruin of the unregenerate. He is encouraged, in his repentance, to hope that God would graciously accept him. Thou desirest truth in the inward part; to this God looks, in a returning sinner. Where there is truth, God will give wisdom. Those who sincerely endeavour to do their duty shall be taught their duty; but they will expect good only from Divine grace overcoming their corrupt nature.

Wash me throughly. It is not enough to blot out the sin; his person is defiled, and he fain would be purified. He would have God himself cleanse him, for none but he could do it effectually. The washing must be thorough, it must be repeated, therefore he cries, "Multiply to wash me." The dye is in itself immovable, and I, the sinner, have lain long in it, till the crimson is ingrained; but, Lord, wash, and wash, and wash again, till the last stain is gone, and not a trace of my defilement is left. The hypocrite is content if his garments be washed, but the true suppliant cries, "wash me." The careless soul is content with a nominal cleansing, but the truly awakened conscience desires a real and practical washing, and that of a most complete and efficient kind. Wash me throughly from mine iniquity. It is viewed as one great pollution, polluting the entire nature, and as all his own; as if nothing were so much his own as his sin. The one sin against Bathsheba, served to show the psalmist the whole mountain of his iniquity, of which that foul deed was but one falling stone. He desires to be rid of the whole mass of his filthiness, which though once so little observed, had then become a hideous and haunting terror to his mind. And cleanse me from my sin. This is a more general expression; as if the psalmist said, "Lord, if washing will not do, try some other process; if water avails not, let fire, let anything be tried, so that I may but be purified. Rid me of my sin by some means, by any means, by every means, only do purify me completely, and leave no guilt upon my soul." It is not the punishment he cries out against, but the sin. Many a murderer is more alarmed at the gallows than at the murder which brought him to it. The thief loves the plunder, though he fears the prison. Not so David: he is sick of sin as sin; his loudest outcries are against the evil of his transgression, and not against the painful consequences of it. When we deal seriously with our sin, God will deal gently with us. When we hate what the Lord hates, he will soon make an end of it, to our joy and peace.