Add iniquity to their iniquity; let them not share in Your righteousness.
PSALM 69 There is a close resemblance between this psalm and the twenty-second. In the opening verses, David complains of the barbarous cruelty of his enemies, and of the grievous wrongs which they had inflicted upon him. The particular enemies of whom he speaks are uncertain; some referring the occasion of the composition of the psalm to his persecution by Saul, and others to the rebellion of Absalom.
Commenting on Psalm 69:1-36
Add iniquity unto their iniquity. Unbelievers will add sin to sin, and so, punishment to punishment. This is the severest imprecation, or prophecy, of all. For men to be let alone to fill up the measure of their iniquity, is most equitable, but yet most awful. And let them not come into thy righteousness. If they refuse it, and resist thy gospel, let them shut themselves out of it.
These imprecations are not David's prayers against his enemies, but prophecies of the destruction of Christ's persecutors, especially the Jewish nation, which our Lord himself foretold with tears, and which was accomplished about forty years after the death of Christ.
Commenting on Psalm 69:22-29