Jeremiah 6:27-30 World English Bible (WEB)

27. “I have made you a tester of metals and a fortress among my people; that you may know and try their way.

28. They are all grievous rebels, going about with slanders; they are brass and iron: they all of them deal corruptly.

29. The bellows blow fiercely; the lead is consumed of the fire: in vain do they go on refining; for the wicked are not plucked away.

30. Men will call them rejected silver, because Yahweh has rejected them.”

Jeremiah 6