Leviticus 13:4-8

“If the shiny spot on the skin is white but appears to be only on the surface and the hair has not turned white, the priest will quarantine the person for seven days. On the seventh day the priest will examine it again; if, in his judgment, the sore is the same and has not spread, the priest will keep him in quarantine for another seven days. On the seventh day the priest will examine him a second time; if the sore has faded and hasn’t spread, the priest will declare him clean—it is a harmless rash. The person can go home and wash his clothes; he is clean. But if the sore spreads after he has shown himself to the priest and been declared clean, he must come back again to the priest who will conduct another examination. If the sore has spread, the priest will pronounce him unclean—it is a serious skin disease and infectious.