Jeremiah 6:28-30

They are all the worst [kind] of [stiff-necked, godless] rebels, Going around spreading slander. They are [not gold and silver ore, but] bronze and iron; They are all corrupt. The bellows blow fiercely, The lead is consumed by the fire; In vain they continue refining, But the wicked are not separated and removed. They call them rejected silver [only dross, without value], Because the LORD has rejected them.