Leviticus 13:29-33

29"When a man or woman has a disease on the head or the beard,

30the priest shall examine the disease. And if it appears deeper than the skin, and the hair in it is yellow and thin, then the priest shall pronounce him unclean. It is an itch, a leprous disease of the head or the beard.

31And if the priest examines the itching disease and it appears no deeper than the skin and there is no black hair in it, then the priest shall shut up the person with the itching disease for seven days,

32and on the seventh day the priest shall examine the disease. If the itch has not spread, and there is in it no yellow hair, and the itch appears to be no deeper than the skin,

33then he shall shave himself, but the itch he shall not shave; and the priest shall shut up the person with the itching disease for another seven days.