Leviticus 13:2-3

2“When someone has on the skin of his 1body a swelling, or a scab, or a bright spot, and it becomes an infection of 2leprosy on the skin of his 3body, 4then he shall be brought to Aaron the priest or to one of his sons the priests.

3The priest shall look at the infected area on the skin of the 5body, and if the hair in the infection has turned white and the infection appears to be deeper than the skin of his 6body, it is an infection of leprosy; when the priest has looked at him, he shall pronounce him unclean.