Leviticus 13:6-8

6On the seventh day the priest will make another examination. If he finds the affected area has faded and has not spread, the priest will pronounce the person ceremonially clean. It was only a rash. The person’s clothing must be washed, and the person will be ceremonially clean.

7But if the rash continues to spread after the person has been examined by the priest and has been pronounced clean, the infected person must return to be examined again.

8If the priest finds that the rash has spread, he must pronounce the person ceremonially unclean, for it is indeed a skin disease.