Numbers 31:19-24

19And as for you, remain outside the camp seven days; whoever has killed any person, and whoever has touched any slain, purify yourselves and your captives on the third day and on the seventh day.

20Purify every garment, everything made of leather, everything woven of goats’ hair, and everything made of wood.”

21Then 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:

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

23everything 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.

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