Leviticus 13:1-3

And the Lord said to Moses and Aaron, If a man has on his skin a growth or a mark or a white place, and it becomes the disease of a leper, let him be taken to Aaron the priest, or to one of the priests, his sons; And if, when the priest sees the mark on his skin, the hair on the place is turned white and the mark seems to go deeper than the skin, it is the mark of a leper: and the priest, after looking at him, will say that he is unclean.