Leviticus 13:2-3, 44-46

“Someone might have on his skin a swelling or a rash or a bright spot. If the sore looks like a harmful skin disease, the person must be brought to Aaron the priest or to one of Aaron’s sons, the priests. The priest must look at the sore on the person’s skin. If the hair in the sore has become white, and the sore seems deeper than the person’s skin, it is a harmful skin disease. When he has finished looking at the person, the priest must announce that the person is unclean.

that person has a skin disease. He is unclean. The priest must announce that the person is unclean because of the sore on his head. “If a person has a skin disease that spreads, he must warn other people by shouting, ‘Unclean, unclean!’ His clothes must be torn at the seams, he must let his hair stay uncombed, and he must cover his mouth. That person will be unclean the whole time he has the disease; he is unclean. He must live alone outside the camp.