Numbers 31:22-24

22only the gold, the silver, the bronze, the iron, the tin, and the lead,

23everything that can stand fire, you shall pass through fire, and it shall be clean. Nevertheless, it shall also be purified with the water of purification [to remove its impurity]; and all that cannot stand fire [such as fabrics] you shall pass through water.

24And you shall wash your clothes on the seventh day and be clean, and afterward you may come into the camp.”