If the bright spot be white in the skin of his flesh,.... The Targum of Jonathan is, white as chalk in the skin of his flesh; but other Jewish writers make the whiteness of the bright spot to be the greatest of all, like that of snow; See Gill on Leviticus 13:2,

and in sight be not deeper than the skin, and the hair thereof be not turned white; though it be a bright spot, and be very white, yet these two marks not appearing, it cannot be judged a leprosy, at most it is only suspicious: wherefore

then the priest, shall shut up him that hath the plague seven days; in whom the bright spot is, and of whom there is a suspicion of the plague of leprosy, but it is not certain; and therefore, in order to take time, and get further knowledge, the person was to be shut up from all company and conversation for the space of seven days; by which time it might be supposed, as Ben Gersom observes, that the case and state of the leprosy (if it was one) would be altered; and Aben Ezra remarks, that most diseases change or alter on the seventh day.

But if the bright spot was white upon the skin, and its appearance was not deeper than the skin, and the place therefore was not sunken, nor the hair turned white, the priest was to shut up the leper, i.e., preclude him from intercourse with other men, for seven days, and on the seventh day examine him again. If he then found that the mole still stood, i.e., remained unaltered, "in his eyes," or in his view, that it had not spread any further, he was to shut him up for seven days more. And if, on further examination upon the seventh day, he found that the mole had become paler, had lost its brilliant whiteness, and had not spread, he was to declare him clean, for it was a scurf, i.e., a mere skin eruption, and not true leprosy. The person who had been pronounced clean, however, was to wash his clothes, to change himself from even the appearance of leprosy, and then to be clean.

If the bright spot be white in the skin of his flesh, and in sight be not deeper than the skin, and the hair thereof be not turned white; then the priest shall shut up him that hath the plague seven days:

13:4 Seven days - For greater assurance; to teach ministers not to be hasty in their judgments, but diligently to search and examine all things before - hand. The plague is here put for the man that hath the plague.

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?