18 And the flesh—when in the skin thereof cometh a boil, and it is healed, 19 and there is in the place of the boil a white rising, or a white-reddish bright spot, it shall be shewn to the priest; 20 and the priest shall look on it, and behold, it looketh deeper than the skin, and the hair thereof is turned white; then the priest shall pronounce him unclean: it is the sore of leprosy broken out in the boil. 21 But if the priest look on it, and behold, there are no white hairs therein, and it is not deeper than the skin, and is pale, the priest shall shut him up seven days; 22 and if it spread much in the skin, then the priest shall pronounce him unclean: it is the sore. 23 But if the bright spot have remained in its place, [and] have not spread, it is the scar of the boil; and the priest shall pronounce him clean.
Matthew Henry's Commentary on Leviticus 13:18-23
Commentary on Leviticus 13:18-44
(Read Leviticus 13:18-44)
The priest is told what judgment to make, if there were any appearance of a leprosy in old sores; and such is the danger of those who having escaped the pollutions of the world are again entangled therein. Or, in a burn by accident, verse 24. The burning of strife and contention often occasions the rising and breaking out of that corruption, which proves that men are unclean. Human life lies exposed to many grievances. With what troops of diseases are we beset on every side; and thy all entered by sin! If the constitution be healthy, and the body lively and easy, we are bound to glorify God with our bodies. Particular note was taken of the leprosy, if in the head. If the leprosy of sin has seized the head; if the judgment be corrupted, and wicked principles, which support wicked practices, are embraced, it is utter uncleanness, from which few are cleansed. Soundness in the faith keeps leprosy from the head.