The scall shall he not shave - Lest the place should be irritated and inflamed, and assume in consequence other appearances besides those of a leprous infection; in which case the priest might not be able to form an accurate judgment.

He shall be shaven,.... His head or beard, where the scall was, as Aben Ezra; and so Ben Gersom, who adds, the law is not solicitous whether this shaving is by a priest or not; so it seems any one might shave him:
but the scall shall he not shave; that is, the hair that is in it, but that was to continue and grow, that the colour of it might be easily discerned at the end of seven other days; according to the Targums of Onkelos and Jonathan, he was to shave round about it, but not that itself; Jarchi says, he was to leave two hairs near it (u), that he might know whether it spread; for if it spread it would go over the hairs, and into the part that was shaven; when it would be a clear case it was a spreading leprosy: now, that there might be an opportunity of observing this, whether it would or not, the following method was to be taken:
and the priest shall shut up him that hath the scall seven days more; by which time it would be seen whether there was any increase or decrease, or whether at a stand, and of what colour the hair was, by which judgment might be made of the case.
(u) Misn. Negaim, c. 10. sect. 5.

He shall be shaven - For the more certain discovery of the growth or stay of the plague.