At last I took up a full resolution, that I would no longer daily nor deal deceitfully with God, nor vainly seek to hide my sins from the all-seeing God, but that I would openly and candidly confess and bewail all my sins with all their aggravations, and humbly implore the pardon of them. The iniquity of my sin, i.e. the guilt of my sin. Or, Thou didst take away the punishment (as this Hebrew word oft signifies) of my sin; or, my exceeding sinful sin; two words signifying the same thing, being here put together by way of aggravation, according to the manner of the Hebrews.
Related Commentaries of Psalms 32:5
Psalms 32:5
5 I acknowledged my sin unto thee, and mine iniquity have I not hid. I said, I will confess my transgressions unto the LORD; and thou forgavest the iniquity of my sin. Selah.