Leviticus 13:18-20

“And when there is on the skin of the body [the scar of] a boil that is healed, and in the place of the boil there is a white swelling or a bright spot, reddish white, then it shall be shown to the priest; and the priest shall look, and if it looks deeper than the skin and the hair on it has turned white, the priest shall pronounce him unclean; it is the disease of leprosy; it has broken out in the boil.