Jeremiah 6:28-30 Amplified Bible (AMP)

28. They are all the worst [kind] of rebels and utter and total revolters against God, going about publishing slander. They are [not gold and silver ore, but] bronze and iron; they are all corrupters.

29. The bellows blow fiercely, the lead is consumed by the fire; in vain do they continue refining, for the wicked [the dross] are not removed.

30. Men will call them reprobate and rejected silver [only dross, without good metal], because the Lord has rejected them.

Jeremiah 6