Leviticus 13:29-37

“If a man or woman develops a sore on the head or chin, the priest will offer a diagnosis. If it looks as if it is under the skin and the hair in it is yellow and thin, he will pronounce the person ritually unclean. It is an itch, an infectious skin disease. But if when he examines the itch, he finds it is only skin deep and there is no black hair in it, he will put the person in quarantine for seven days. On the seventh day he will reexamine the sore; if the itch has not spread, there is no yellow hair in it, and it looks as if the itch is only skin deep, the person must shave, except for the itch; the priest will send him back to quarantine for another seven days. If the itch has not spread, and looks to be only skin deep, the priest will pronounce him clean. The person can go home and wash his clothes; he is clean. But if the itch spreads after being pronounced clean, the priest must reexamine it; if the itch has spread in the skin, he doesn’t have to look any farther, for yellow hair, for instance; he is unclean. But if he sees that the itch is unchanged and black hair has begun to grow in it, the itch is healed. The person is clean and the priest will pronounce him clean.