Numbers 31:19-24

19All of you who have killed a person or touched the dead are to remain outside the camp for seven days. On the third day and the seventh day you are to purify both yourselves and your captives. 20And purify every garment and leather good, everything made of goat’s hair, and every article of wood.”

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. 24On the seventh day you are to wash your clothes, and you will be clean. After that you may enter the camp.”