Numbers 31:20

16 “Look, these women caused the sons of Israel, through the counsel of Balaam, to turn unfaithfully against the LORD at Peor, so that the plague struck the congregation of the LORD.

17 So now, kill all the boys, as well as every woman who has had relations with a man,

18 but spare for yourselves every girl who has never had relations with a man.

19 All 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.

20 And purify every garment and leather good, everything made of goat’s hair, and every article of wood.”

21 Then 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:

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

23 everything 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.

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

Read all of Numbers 31