Numbers 31:22-24

Complete Jewish Bible

²² Even though gold, silver, brass, iron, tin and lead ²³ can all withstand fire, so that you are indeed to purify everything made of these materials by having them pass through fire; nevertheless they must also be purified with the water for purification. Everything that can’t withstand fire you are to have go 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.”