and shall kill one of the birds in an earthenware vessel over fresh water
This is the law concerning the leprosy in a house. Now that they were in the wilderness they dwelt in tents, and had no houses, and therefore the law is made only an appendix to the former laws concerning the leprosy, because it related, not to their present state, but to their future settlement.
Commenting on Leviticus 14:33-53
Lev 14:48-53 If the priest should find, however, that after the fresh plastering the mole had not appeared again, or spread (to other places), he was to pronounce the house clean, because the evil was cured, and (Lev 14:49-53) to perform the same rite of purification as was prescribed for the restoration of a man, who had been cured of leprosy, to the national community (Lev 14:4-7).
Commenting on Leviticus 14:48-53