18 "And when there is in the skin of one's body a boil that has healed, 19 and in the place of the boil there comes a white swelling or a reddish-white spot, then it shall be shown to the priest; 20 and the priest shall make an examination, and if it appears deeper than the skin and its hair has turned white, then the priest shall pronounce him unclean; it is the disease of leprosy, it has broken out in the boil. 21 But if the priest examines it, and the hair on it is not white and it is not deeper than the skin, but is dim, then the priest shall shut him up seven days; 22 and if it spreads in the skin, then the priest shall pronounce him unclean; it is diseased. 23 But if the spot remains in one place and does 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.