Charles Ellicott Commentary Jeremiah 50:7

"All that found them have devoured them; and their adversaries said, We are not guilty, because they have sinned against Jehovah, the habitation of righteousness, even Jehovah, the hope of their fathers." — Jeremiah 50:7 (ASV)

Their adversaries said, We offend not ... —These words are suggestive, indicating a special aspect of the prophet's thoughts concerning the idolatry of Judah. What was for him its utmost humiliation was that it put a taunt into the mouths of her people's enemies. They were able to say, “We are acting rightly: we are but instruments in the hands of God.” The words that follow can hardly be considered those of Israel's enemies, but rather as words added by the prophet to emphasize the guilt of his own people.