Leviticus 13:9

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.

6 The priest will examine him again on the seventh day, and if the sore has faded and has not spread on the skin, the priest shall pronounce him clean; it is a rash. The person must wash his clothes and be clean.

7 But if the rash spreads further on his skin after he has shown himself to the priest for his cleansing, he must present himself again to the priest.

8 The priest will reexamine him, and if the rash has spread on the skin, the priest must pronounce him unclean; he has a skin disease.

9 When anyone develops a skin disease, he must be brought to the priest.

10 The priest will examine him, and if there is a white swelling on the skin that has turned the hair white, and there is raw flesh in the swelling,

11 it is a chronic skin disease and the priest must pronounce him unclean. He need not isolate him, for he is unclean.

12 But if the skin disease breaks out all over his skin so that it covers all the skin of the infected person from head to foot, as far as the priest can see,

13 the priest shall examine him, and if the disease has covered his entire body, he is to pronounce the infected person clean. Since it has all turned white, he is clean.

Read all of Leviticus 13