Numbers 5:27
5:27 When he has made her drink the water, then, if she has defiled herself and behaved unfaithfully toward her husband, the water that brings a curse will enter her to produce bitterness – her abdomen will swell, her thigh will fall away, and the woman will become a curse among her people.
Numbers 31:23
31:23 everything that may stand the fire, you are to pass through the fire, 1 and it will be ceremonially clean, but it must still be purified with the water of purification. Anything that cannot withstand the fire you must pass through the water.
1 sn Purification by fire is unique to this event. Making these metallic objects “pass through the fire” was not only a way of purifying (burning off impurities), but it seems to be a dedicatory rite as well to the Lord and his people. The aspect of passing through the fire is one used by these pagans for child sacrifice.