Charles H. Spurgeon on Psalms 65:3

The holy prophets, and penmen of Scripture, have no grounds of hope for pardon of sin, save those which are common to the meanest of God's people; for David, in his confession, cometh in by himself alone, aggravating his own sins most: Iniquities prevail against me, saith he. But in hope of pardon, he joins with the rest of God's people, saying, As for our transgressions, thou shalt purge them away. David Dickson.

Verses 3-4. Now, soul, thou art molested with many lusts that infect thee, and obstruct thy commerce with heaven; yea, thou hast complained to thy God, what loss thou hast suffered by them; is it now presumption to expect relief from him, that he will rescue thee from them, that thou mayest serve him without fear, who is thy liege Lord? You have the saints for your precedents; who, when they have been in combat with their corruptions, yea, been foiled by them, have even then exercised their faith on God, and expected the ruin of those enemies, which, for the present, have overrun them. Iniquities prevail against me; he means his own sins; but see his faith; at the same time that they prevailed over him, he beholds God destroying them, as appears in the very next words, As for our transgressions, thou shalt purge them away. See here, poor Christian, who thinkest that thou shalt never get above deck, holy David has a faith, not only for himself, but also for all believers, of whose number I suppose thee one. And mark the ground he hath for this his confidence, taken from God's choosing act: Blessed is the man whom thou choosest, and causest to approach unto thee, that he may dwell in thy courts. As if he had said, Surely he will not let them be under the power of sin, or in want of his gracious succour, whom he sets so near himself. This is Christ's own argument against Satan, in the behalf of his people. "The Lord said unto Satan, the Lord rebuke thee." Zec 3:2. William Gurnall.