And the priest shall look on the plague in the skin of the flesh: and when the hair in the plague is turned white, and the plague in sight be {b} deeper than the skin of his flesh, it is a plague of leprosy: and the priest shall look on him, and pronounce him unclean.

(b) That is, shrunken in, and be lower than the rest of the skin.

Wesley's Notes

13:3 When the hair is turned white - This change of colour was an evidence both of the abundance of excrementious humours, and of the weakness of nature, as we see in old and sick persons. His flesh - For the leprosy consumed both the skin and the flesh.

Scofield Reference Notes

[2] priest

Some have found in the regulations of this chapter concerning an inquest by the priest of a case of leprosy, elaborate provisions for the exercise of discipline in the local church. No little self-righteousness and cruelty have come in thereby. The explicit instructions of the N.T. are the alone and sufficient rule of discipline.

Jamieson-Fausset-Brown Bible Commentary

3-6. the priest shall look on the plague in the skin of the flesh, &c.-The leprosy, as covering the person with a white, scaly scurf, has always been accounted an offensive blemish rather than a serious malady in the East, unless when it assumed its less common and malignant forms. When a Hebrew priest, after a careful inspection, discovered under the cutaneous blemish the distinctive signs of contagious leprosy, the person was immediately pronounced unclean, and is supposed to have been sent out of the camp to a lazaretto provided for that purpose. If the symptoms appeared to be doubtful, he ordered the person to be kept in domestic confinement for seven days, when he was subjected to a second examination; and if during the previous week the eruption had subsided or appeared to be harmless, he was instantly discharged. But if the eruption continued unabated and still doubtful, he was put under surveillance another week; at the end of which the character of the disorder never failed to manifest itself, and he was either doomed to perpetual exclusion from society or allowed to go at large. A person who had thus been detained on suspicion, when at length set at liberty, was obliged to "wash his clothes," as having been tainted by ceremonial pollution; and the purification through which he was required to go was, in the spirit of the Mosaic dispensation, symbolical of that inward purity it was instituted to promote.

Matthew Henry's Concise Commentary

13:1-17 The plague of leprosy was an uncleanness, rather than a disease. Christ is said to cleanse lepers, not to cure them. Common as the leprosy was among the Hebrews, during and after their residence in Egypt, we have no reason to believe that it was known among them before. Their distressed state and employment in that land must have rendered them liable to disease. But it was a plague often inflicted immediately by the hand of God. Miriam's leprosy, and Gehazi's, and king Uzziah's, were punishments of particular sins; no marvel there was care taken to distinguish it from a common distemper. The judgment of it was referred to the priests. And it was a figure of the moral pollutions of men's minds by sin, which is the leprosy of the soul, defiling to the conscience, and from which Christ alone can cleanse. The priest could only convict the leper, (by the law is the knowledge of sin,) but Christ can cure the sinner, he can take away sin. It is a work of great importance, but of great difficulty, to judge of our spiritual state. We all have cause to suspect ourselves, being conscious of sores and spots; but whether clean or unclean is the question. As there were certain marks by which to know it was leprosy, so there are marks of such as are in the gall of bitterness. The priest must take time in making his judgment. This teaches all, both ministers and people, not to be hasty in censures, nor to judge anything before the time. If some men's sins go before unto judgment, the sins of others follow after, and so do men's good works. If the person suspected were found to be clean, yet he must wash his clothes, because there had been ground for the suspicion. We have need to be washed in the blood of Christ from our spots, though not leprosy spots; for who can say, I am pure from sin?