Numbers 31:23

²¹  And Eleazar the priest said unto the men of war which went to the battle, This is the ordinance of the law which the LORD commanded Moses;

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

²³  Every thing that may abide the fire, ye shall make it go through the fire, and it shall be clean: nevertheless it shall be purified with the water of separation: and all that abideth not the fire ye shall make go through the water.

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

²⁵  And the LORD spake unto Moses, saying,