Leviticus 13:3

13:3 The priest must then examine the infection on the skin of the body, and if the hair in the infection has turned white and the infection appears to be deeper than the skin of the body, then it is a diseased infection, so when the priest examines it he must pronounce the person unclean.

Leviticus 13:31

13:31 But if the priest examines the scall infection and it does not appear to be deeper than the skin, and there is no black hair in it, then the priest is to quarantine the person with the scall infection for seven days.