Leviticus 13:18-20

“When someone has a boil on their skin and it heals, and in the place where the boil was, a white swelling or reddish-white spot appears, they must present themselves to the priest. The priest is to examine it, and if it appears to be more than skin deep and the hair in it has turned white, the priest shall pronounce that person unclean. It is a defiling skin disease that has broken out where the boil was.