And the plague spread not - Rather, advance not, so as to show that the disease is under the cuticle and assuming the symptoms of Leviticus 13:3.

And the priest shall look on him the seventh day,.... In the day, and not in the night, as Maimonides, but not on the seventh day, if it happened to be on the sabbath (f), then it was put off till after it; and, according to the Jewish canons (g), they do not look upon plagues in the morning, nor in the evening, nor in the middle of a house, nor on a cloudy day, nor at noon, but at the fourth, fifth, eighth, and ninth hours:

and, behold, if the plague in his sight be at a stay; it appears to the priest, according to the strictest view he can take of it, that it is in the same state and condition it was, neither better nor worse:

and the plague spread not in the skin: is not greater or larger than it was, though not less:

then the priest shall shut him up seven days more; such abundant care was taken, lest after all it should prove a leprosy.

(f) Misn. Negaim, c. 1. sect. 4. (g) Misn. ib. c. 2. sect. 2.

And the priest shall look on him the seventh day: and, behold, if the plague in his sight be at a stay, and the plague spread not in the skin; then the priest shall shut him up seven days more:

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?