Leviticus 13:2-8

2“When anyone has a swelling or a rash or a shiny spot on their skin that may be a defiling skin disease, they must be brought to Aaron the priest or to one of his sons who is a priest. 3The priest is to examine the sore on the skin, and if the hair in the sore has turned white and the sore appears to be more than skin deep, it is a defiling skin disease. When the priest examines that person, he shall pronounce them ceremonially unclean. 4If the shiny spot on the skin is white but does not appear to be more than skin deep and the hair in it has not turned white, the priest is to isolate the affected person for seven days. 5On the seventh day the priest is to examine them, and if he sees that the sore is unchanged and has not spread in the skin, he is to isolate them for another seven days. 6On the seventh day the priest is to examine them again, and if the sore has faded and has not spread in the skin, the priest shall pronounce them clean; it is only a rash. They must wash their clothes, and they will be clean. 7But if the rash does spread in their skin after they have shown themselves to the priest to be pronounced clean, they must appear before the priest again. 8The priest is to examine that person, and if the rash has spread in the skin, he shall pronounce them unclean; it is a defiling skin disease.