Leviticus 13:20-23

²⁰The priest shall inspect it, and if it seems to be more than something on the surface, and if the hair there has turned white, the priest shall declare him unclean. It is a serious skin disease that has infected the boil.

²¹However, if when the priest inspects it, it doesn't have white hair in it and doesn't seem to be more than superficial, and has faded, the priest is to place the person in isolation for seven days.

²²If then the spot has spread further on the skin, the priest will declare them unclean; it is a disease.

²³But if the spot stays the same and doesn't spread, it's just the scar from the boil, and the priest will declare them clean.