Leviticus 13:13-17

Then the priest shall consider: and, behold, if the leprosy have covered all his flesh, he shall pronounce him clean that hath the plague: it is all turned white: he is clean.

But when raw flesh appeareth in him, he shall be unclean.

And the priest shall see the raw flesh, and pronounce him to be unclean: for the raw flesh is unclean: it is a leprosy.

Or if the raw flesh turn again, and be changed unto white, he shall come unto the priest;

And the priest shall see him: and, behold, if the plague be turned into white; then the priest shall pronounce him clean that hath the plague: he is clean.