Jeremiah 50:20 - Matthew Poole's English Annotations on the Holy Bible

Some here restrain the term iniquity to the idolatry of the Jews, which indeed was their great sin, which God did more especially punish them for; and after the captivity of Babylon we do not read of their offending in that kind, which was according to the prophecy of Isaiah 27:9, that when God should make the stones of the altar as chalk-stones that are beaten asunder, the groves and the images should not stand up. But the last words seem to guide us to a larger sense of the term iniquity, and to point us to another sense of the whole former phrase, viz. that God would no longer punish the sins of the Jews; they should be sought for as to punishment, and not found. And those words and none must be understood as if none, they shall be punished no, more than if they had none. For I will pardon them whom I reserve; for as to those whom I save from the captivity of Babylon, I will pardon them: not that they were all excused from the obligation their sins laid them under as, to eternal death, but that their temporal punishment was remitted to the whole body of the Jews, and those that were truly penitent also should be discharged from their obligation to eternal death. The obligation that sin layeth the sinner under to eternal death may be remitted, and yet the temporal punishment due to them may remain, 2 Samuel 12:13,14, &c. And, on the other side, the punishment in this life may be suspended or remitted, and the obligation sin layeth the sinner under to eternal death may remain.