Leviticus 13:2-3

2“When a person has a swelling, scab, or spot on the skin of his body, and it may be a serious disease on the skin of his body, he is to be brought to the priest Aaron or to one of his sons, the priests.

3The priest will examine the sore on the skin of his body. If the hair in the sore has turned white and the sore appears to be deeper than the skin of his body, it is in fact a serious skin disease. After the priest examines him, he must pronounce him unclean.