Leviticus 13:18-23

“When a boil appears on the skin  of someone’s body  and it heals, and a white swelling or a reddish-white spot develops where the boil was, the person is to present himself to the priest. The priest will make an examination, and if the spot seems to be beneath the skin and the hair in it has turned white, the priest must pronounce him unclean; it is a case of serious skin disease that has broken out in the boil. But when the priest examines it, if there is no white hair in it, and it is not beneath the skin but is faded, the priest will quarantine him seven days. If it spreads further on the skin, the priest must pronounce him unclean; it is in fact a disease. But if the spot remains where it is and does not spread, it is only the scar from the boil. The priest is to pronounce him clean.