Leviticus 13:5-8

5and the priest shall look on him the seventh day: and, behold, if in his eyes the plague be at a stay, and the plague be not spread in the skin, then the priest shall shut him up seven days more:

6and the priest shall look on him again the seventh day: and, behold, if the plague be dim, and the plague be not spread in the skin, then the priest shall pronounce him clean: it is a scab: and he shall wash his clothes, and be clean.

7But if the scab spread abroad in the skin, after that he hath shewn himself to the priest for his cleansing, he shall shew himself to the priest again:

8and the priest shall look, and, behold, if the scab be spread in the skin, then the priest shall pronounce him unclean: it is leprosy.