Leviticus 13:1

1 Then the LORD said to Moses and Aaron,

2 “When someone has a swelling or rash or bright spot on his skin that could become an infectious skin disease, he must be brought to Aaron the priest or to one of his sons who is a priest.

3 The 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.

4 If, 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.

5 On the seventh day the priest is to reexamine him, and if he sees that the infection is unchanged and has not spread on the skin, the priest must isolate him for another seven days.

Read all of Leviticus 13