(1) Blot out.--The figure is most probably, as in Exodus 32:32-33, taken from the custom of erasing a written record (comp. Numbers 5:23; Psalm 69:28). So LXX. and Vulg. Isaiah, however (Isaiah 44:22) uses the same word in a different connection, "I will blot out thy sins as a cloud." A fine thought that the error and guilt that cloud the mind and conscience can be cleared off like a mist by a breath from heaven.

Transgressions.--See Psalm 32:1. The word seems to imply a wilful throwing off of authority or restraint, perhaps here the breach of the covenant-relation irrespective of any particular sin by which the breach was brought about. Whether it is an individual or the community that speaks, the prayer is that Jehovah would act according to His chesed or covenant-favour towards the suppliant, and wipe out from His records whatever has intervened between the covenant parties.

Verse 1. - Have mercy upon me, O God, according to thy loving-kindness. It is observable that the whole psalm is addressed to God (Elohim), and not to Jehovah (the "Lord" in ver. 15 is Adonai), as though the psalmist felt himself unworthy to utter the covenant-name, and simply prostrated himself as a guilty man before his offended Maker. It is not correet to say that "loving-kindness implies a covenant" (Cheyne), since God is "good to all, and his tender mercies are over all his works" (Psalm 145:9). According unto the multitude of thy tender mercies blot out my transgressions. David's first prayer is for pity; his second, to have his offences "blotted out," or "wiped out" - entirely removed from God's book (comp. Exodus 32:32; Isaiah 43:25; Isaiah 44:22). He says "my transgressions," in the plural, because "his great sin did not stand alone - adultery was followed by treachery and murder" (Canon Cook).

51:1-6 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.Have mercy upon me, O God,.... David, under a sense of sin, does not run away from God, but applies unto him, and casts himself at his feet, and upon his mercy; which shows the view he had of his miserable condition, and that he saw there was mercy in God, which gave him hope; and upon his bended knees, and in the exercise of faith, he asks for it;

according to thy lovingkindness; not according to his merits, nor according to the general mercy of God, which carnal men rely upon; but according to his everlasting and unchangeable love in Christ; from which as the source, and through whom as the medium, special mercy comes to the children of men. The acts of special mercy are according to the sovereign will of God: he is not moved to mercy neither by the merits nor misery of men, but by his free grace and favour; it is love that sets mercy to work: this is a most glaring gleam of Gospel light, which none of the inspired writers besides, except the Apostle Paul, saw, Ephesians 2:4;

according unto the multitude of thy tender mercies blot out my transgressions; for his sin was complicated, attended with many others; and, besides, upon a view of this, he was led to observe all his other sins; and particularly the corruption of his nature, his original sin, which he mentions, Psalm 51:5. These he desires might be "blotted out"; out of the book of account, out of God's debt book; that they might not stand against him, being debts he was not able to pay or make satisfaction for; and out of the table of his own heart and conscience, where they were ever before him, and seemed to be engraven; that they might be caused to pass from him, and he might have no more conscience of them; or that they might be blotted out, as a cloud by the clear shining of the sun of righteousness, with the healing of pardoning grace in his wings; or that they might be wiped away, as any faith is wiped from any person or thing: and all this "according to the multitude of his tender mercies". The mercy of God is plenteous and abundant; he is rich in it, and various are the instances of it; and it is exceeding tender, like that of a father to his children, or like that of a mother to the son of her womb; and from this abundant and tender mercy springs the forgiveness of sin, Luke 1:77. The psalmist makes mention of the multitude of the mercies of God, because of the multitude of his sins, which required a multitude of mercy to forgive, and to encourage his hope of it.