Numbers 31:19-21

American Standard Version

¹⁹ And encamp ye without the camp seven days: whosoever hath killed any person, and whosoever hath touched any slain, purify yourselves on the third day and on the seventh day, ye and your captives. ²⁰ And as to every garment, and all that is made of skin, and all work of goats’ hair, and all things made of wood, ye shall purify yourselves.

²¹ And Eleazar the priest said unto the men of war that went to the battle, This is the statute of the law which Jehovah hath commanded Moses: