Leviticus 13:18-22

“Now when the body has a boil on its skin and it is healed,

and in the place of the boil there is a white swelling or a reddish-white, bright spot, then it shall be shown to the priest;

and the priest shall look, and behold, if it appears to be deeper than the skin, and the hair on it has turned white, then the priest shall pronounce him unclean; it is the infection of leprosy, it has broken out in the boil.

But if the priest looks at it, and behold, there are no white hairs in it and it is not deeper than the skin and is faded, then the priest shall isolate him for seven days;

and if it spreads farther on the skin, then the priest shall pronounce him unclean; it is an infection.