Numbers 31:21-24

Then Eleazar the priest said to the men of war who had gone to the battle, “This is the ordinance of the law which the LORD commanded Moses: Only the gold, the silver, the bronze, the iron, the tin, and the lead, everything that can endure fire, you shall put through the fire, and it shall be clean; and it shall be purified with the water of purification. But all that cannot endure fire you shall put through water. And you shall wash your clothes on the seventh day and be clean, and afterward you may come into the camp.”