We have here,
I. Provisos that neither a freckled skin nor a bald head should be mistaken for a leprosy, Lev 13:38-41. Every deformity must not forthwith be made a ceremonial defilement. Elisha was jeered for his bald head (Kg2 2:23); but it was the children of Bethel, that knew not the judgments of their God, who turned it to his reproach.
II. A particular brand set upon the leprosy if at any time it did appear in a bald head: The plague is in his head, he is utterly unclean, Lev 13:44. If the leprosy of sin have seized the head, if the judgment be corrupted, and wicked principles which countenance and support wicked practices, be embraced, it is an utter uncleanness, from which few are ever cleansed. Soundness in the faith keeps the leprosy from the head, and saves conscience from being shipwrecked.
III. Directions what must be done with the convicted leper. When the priest, upon mature deliberation, had solemnly pronounced him unclean,
1. He must pronounce himself so, Lev 13:45. He must put himself into the posture of a mourner and cry, Unclean, unclean. The leprosy was not itself a sin, but it was a sad token of God's displeasure and a sore affliction to him that was under it. It was a reproach to his name, put a full stop to his business in the world, cut him off from conversation with his friends and relations, condemned him to banishment till he was cleansed, shut him out from the sanctuary, and was, in effect, the ruin of all the comfort he could have in this world. Heman, it would seem, either was a leper or alludes to the melancholy condition of a leper, Psa 88:8, etc. He must therefore, (1.) Humble himself under the mighty hand of God, not insisting upon his cleanness when the priest had pronounced him unclean, but justifying God and accepting the punishment of his iniquity. He must signify this by rending his clothes, uncovering his head, and covering his upper lip, all tokens of shame and confusion of face, and very significant of that self-loathing and self-abasement which should fill the hearts of penitents, the language of which is self-judging. Thus must we take to ourselves the shame that belongs to us, and with broken hearts call ourselves by our own name, Unclean, unclean - heart unclean, life unclean, unclean by original corruption, unclean by actual transgression - unclean, and therefore worthy to be for ever excluded from communion with God, and all hope of happiness in him. We are all as an unclean thing (Isa 64:6) - unclean, and therefore undone, if infinite mercy do not interpose. (2.) He must give warning to others to take heed of coming near him. Wherever he went, he must cry to those he saw at a distance, "I am unclean, unclean, take heed of touching me." Not that the leprosy was catching, but by the touch of a leper ceremonial uncleanness was contracted. Every one therefore was concerned to avoid it; and the leper himself must give notice of the danger. And this was all that the law could do, in that it was weak through the flesh; it taught the leper to cry, Unclean, unclean, but the gospel has put another cry into the lepers' mouths, Luk 17:12, Luk 17:13, where we find ten lepers crying with a loud voice, Jesus, Master, have mercy on us. The law only shows us our disease; the gospel shows us our help in Christ.
2. He must then be shut out of the camp, and afterwards, when they came to Canaan, out of the city, town, or village, where he lived, and dwell alone (Lev 13:46), associating with none but those that were lepers like himself. When king Uzziah became a leper, he was banished from his palace, and dwelt in a separate house, Ch2 26:21. And see Kg2 7:3. This typified the purity which ought to be preserved in the gospel church, by the solemn and authoritative exclusion of scandalous sinners, that hate to be reformed, from the communion of the faithful. Put away from among yourselves that wicked person, Co1 5:13.

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.

Then the priest shall look upon it,.... The white reddish sore:

and, behold, if the rising of the sore; or the swelling of it:

be white reddish in his bald head, or in his bald forehead; See Gill on Lev 13:42,

as the leprosy appeareth in the skin of the flesh; as in Lev 13:2; having the signs of the leprosy there given; anyone of them, excepting the white hair, which in this case could be no sign, there being none: Jarchi's note is, according to the appearance of the leprosy, said in Lev 13:2; and what is said in it is, it defiles by four appearances, and is judged in two weeks; but not according to the appearance of the leprosy said of the boil, and burning, which were judged in one week; nor according to the appearance of the scalls, of the place of hair, which do not defile by the four appearances, the rising or swelling, and the scab of it, the bright spot, and the scab of that.

bald . . . forehead bald--The falling off of the hair, when the baldness commences in the back part of the head, is another symptom which creates a suspicion of leprosy. But it was not of itself a decisive sign unless taken in connection with other tokens, such as a "sore of a reddish white color" [Lev 13:43]. The Hebrews as well as other Orientals were accustomed to distinguish between the forehead baldness, which might be natural, and that baldness which might be the consequence of disease.