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.

Numbers 32:22

32:22 and the land is subdued before the Lord, then afterward you may return and be free of your obligation to the Lord and to Israel. This land will then be your possession in the Lord’s sight.

[31:23]  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.