Verse 1-9 — The priests could not cleanse the lepers; but when the Lord removed the plague, various rules were to be observed in admitting them again to the ordinances of God, and the society of his people. They represent many duties and exercises of truly repenting sinners, and the duties of ministers respecting them. If we apply this to the spiritual leprosy of sin, it intimates that when we withdraw from those who walk disorderly, we must not count them as enemies, but admonish them as brethren. And also that when God by his grace has brought to repentance, they ought with tenderness and joy, and sincere affection, to be received again. Care should always be taken that sinners may not be encouraged, nor penitents discouraged. If it were found that the leprosy was healed, the priest must declare it with the particular solemnities here described. The two birds, one killed, and the other dipped in the blood of the bird that was killed, and then let loose, may signify Christ shedding his blood for sinners, and rising and ascending into heaven. The priest having pronounced the leper clean from the disease, he must make himself clean from all remains of it. Thus those who have comfort of the remission of their sins, must with care and caution cleanse themselves from sins; for every one that has this hope in him, will be concerned to purify himself.
Verse 10-32 — The cleansed leper was to be presented to the Lord, with his offerings. When God has restored us to enjoy public worship again, after sickness, distance, or otherwise, we should testify our thanksgiving by our diligent use of the liberty. And both we and our offerings must be presented before the Lord, by the Priest that made us clean, even our Lord Jesus. Beside the usual rites of the trespass-offering, some of the blood, and some of the oil, was to be put upon him that was to be cleansed. Wherever the blood of Christ is applied for justification, the oil of the Spirit is applied for sanctification; these two cannot be separated. We have here the gracious provision the law made for poor lepers. The poor are as welcome to God's altar as the rich. But though a meaner sacrifice was accepted from the poor, yet the same ceremony was used for the rich; their souls are as precious, and Christ and his gospel are the same to both. Even for the poor one lamb was necessary. No sinner could be saved, had it not been for the Lamb that was slain, and hath redeemed us to God with his blood.
Verse 33-53 — The leprosy in a house is unaccountable to us, as well as the leprosy in a garment; but now sin, where that reigns in a house, is a plague there, as it is in a heart. Masters of families should be aware, and afraid of the first appearance of sin in their families, and put it away, whatever it is. If the leprosy is got into the house, the infected part must be taken out. If it remain in the house, the whole must be pulled down. The owner had better be without a dwelling, than live in one that was infected. The leprosy of sin ruins families and churches. Thus sin is so interwoven with the human body, that it must be taken down by death.