Matthew Henry Commentary Leviticus 14:1-9

"And Jehovah spake unto Moses, saying, This shall be the law of the leper in the day of his cleansing: he shall be brought unto the priest: and the priest shall go forth out of the camp; and the priest shall look; and, behold, if the plague of leprosy be healed in the leper, then shall the priest command to take for him that is to be cleansed two living clean birds, and cedar wood, and scarlet, and hyssop: And the priest shall command to kill one of the birds in an earthen vessel over running water. As for the living bird, he shall take it, and the cedar wood, and the scarlet, and the hyssop, and shall dip them and the living bird in the blood of the bird that was killed over the running water: And he shall sprinkle upon him that is to be cleansed from the leprosy seven times, and shall pronounce him clean, and shall let go the living bird into the open field. And he that is to be cleansed shall wash his clothes, and shave off all his hair, and bathe himself in water; and he shall be clean: and after that he shall come into the camp, but shall dwell outside his tent seven days. And it shall be on the seventh day, that he shall shave all his hair off his head and his beard and his eyebrows, even all his hair he shall shave off: and he shall wash his clothes, and he shall bathe his flesh in water, and he shall be clean." — Leviticus 14:1-9 (ASV)

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 practices of truly repenting sinners, and the duties of ministers regarding them. If we apply this to the spiritual leprosy of sin, it suggests that when we withdraw from those who walk disorderly, we must not count them as enemies, but admonish them as brothers.

Furthermore, when God by his grace has brought them to repentance, they should be received again with tenderness, joy, and sincere affection. Care should always be taken that sinners are not encouraged, nor penitents discouraged. If it was found that the leprosy was healed, the priest must declare it with the particular solemnities described here.

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. After the priest had pronounced the leper clean from the disease, the leper must cleanse himself from all its remains. Thus, those who have comfort of the remission of their sins must with care and caution cleanse themselves from sins; for everyone who has this hope in him will be concerned to purify himself.