Numbers 31:22-24

22howbeit the gold, and the silver, the brass, the iron, the tin, and the lead, 23everything that may abide the fire, ye shall make to go through the fire, and it shall be clean; nevertheless it shall be purified with the water for impurity: and all that abideth not the fire ye shall make to go through the water. 24And ye shall wash your clothes on the seventh day, and ye shall be clean; and afterward ye shall come into the camp.