3The priest is to examine the infection on his skin, and if the hair in the infection has turned white and the sore appears to be deeper than the skin, it is a skin disease. After the priest examines him, he must pronounce him unclean.
4If, however, the spot on his skin is white and does not appear to be deeper than the skin, and the hair in it has not turned white, the priest shall isolate the infected person for seven days.
— Leviticus 13:3-4