I will declare mine iniquity - I will confess it with the deepest humiliation and self-abasement.
For I will declare mine iniquity - That is, he was not disposed to hide his sin. He would make no concealment of the fact that he regarded himself as a sinner. He admitted this to be true, and he admitted that his sin was the cause of all his troubles. It was the fact that he was a sinner that so painfully affected his mind; and he was not disposed to attempt to conceal it from anyone.
I will be sorry for my sin - I will not deny it; I will not apologize for it. I admit the truth of what my conscience charges on me; I admit the correctness and the propriety of the divine judgment by which I have been affiicted on account of my sin; I desire to repent of all my transgressions, and to turn from them. Compare Leviticus 26:41. The calamity brought upon the psalmist for his sin had produced the desired effect in this respect, that it had brought him to true repentance; and now, with the full confession of his sin, he was anxious only lest he should fall utterly, and should give his enemies, and the enemies of the truth, the occasion to triumph over him which they desired.