blotted out - the debt of thy sin from the account-book in which it was entered (Exo 32:32, Exo 32:33; Rev 20:12).
as a thick cloud - scattered away by the wind (Psa 103:12).
as a cloud - a descending gradation. Not only the “thick cloud” of the heavier “transgressions,” but the “cloud” (“vapor” [Lowth], not so dense, but covering the sky as a mist) of the countless “sins.” These latter, though not thought much of by man, need, as much as the former, to be cleared away by the Sun of righteousness; else they will be a mist separating us from heaven (Psa 19:12, Psa 19:13; 1Jo 1:7-9).
return ... for - The antecedent redemption is the ground of, and motive to, repentance. We do not repent in order that He may redeem us, but because He hath redeemed us (Zec 12:10; Luk 24:47; Act 3:18, Act 3:19). He who believes in his being forgiven cannot but love (Luk 7:43, Luk 7:47).