29 "If a man or woman has a sore on the head or the beard, 30 then the priest shall examine the sore; and indeed if it appears deeper than the skin, and there is in it thin yellow hair, then the priest shall pronounce him unclean. It is a scaly leprosy of the head or beard. 31 But if the priest examines the scaly sore, and indeed it does not appear deeper than the skin, and there is no black hair in it, then the priest shall isolate the one who has the scale seven days. 32 And on the seventh day the priest shall examine the sore; and indeed if the scale has not spread, and there is no yellow hair in it, and the scale does not appear deeper than the skin, 33 he shall shave himself, but the scale he shall not shave. And the priest shall isolate the one who has the scale another seven days. 34 On the seventh day the priest shall examine the scale; and indeed if the scale has not spread over the skin, and does not appear deeper than the skin, then the priest shall pronounce him clean. He shall wash his clothes and be clean. 35 But if the scale should at all spread over the skin after his cleansing, 36 then the priest shall examine him; and indeed if the scale has spread over the skin, the priest need not seek for yellow hair. He is unclean. 37 But if the scale appears to be at a standstill, and there is black hair grown up in it, the scale has healed. He is clean, and the priest shall pronounce him clean.

Matthew Henry's Commentary on Leviticus 13:29-37

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.