Numbers 31:21-23

21Then Eleazar the priest said to the soldiers who had gone into battle, “This is the statute of the law which the LORD has commanded Moses: 22Only the gold, silver, bronze, iron, tin, and lead— 23everything that can withstand the fire—must be put through the fire, and it will be clean. But it must still be purified with the water of purification. And everything that cannot withstand the fire must pass through the water.