Leviticus 13:2-3

2“When someone has a swelling or a scab or a bright spot on the skin of his body that may become a diseased infection, he must be brought to Aaron the priest or one of his sons, the priests.

3The priest must then examine the infection on the skin of the body, and if the hair in the infection has turned white and the infection appears to be deeper than the skin of the body, then it is a diseased infection, so when the priest examines it he must pronounce the person unclean.