A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
lev 14:2THE RITES AND SACRIFICES IN CLEANSING OF THE LEPER. (Lev. 14:1-57)
law of the leper in the day of his cleansing--Though quite convalescent, a leper was not allowed to return to society immediately and at his own will. The malignant character of his disease rendered the greatest precautions necessary to his re-admission among the people. One of the priests most skilled in the diagnostics of disease [GROTIUS], being deputed to attend such outcasts, the restored leper appeared before this official, and when after examination a certificate of health was given, the ceremonies here described were forthwith observed outside the camp.
lev 14:4two birds--literally, "sparrows." The Septuagint, however, renders the expression "little birds"; and it is evident that it is to be taken in this generic sense from their being specified as "clean"--a condition which would have been altogether superfluous to mention in reference to sparrows. In all the offerings prescribed in the law, Moses ordered only common and accessible birds; and hence we may presume that he points here to such birds as sparrows or pigeons, as in the desert it might have been very difficult to procure wild birds alive.
cedar-wood, and scarlet, and hyssop--The cedar here meant was certainly not the famous tree of Lebanon, and it is generally supposed to have been the juniper, as several varieties of that shrub are found growing abundantly in the clefts and crevices of the Sinaitic mountains. A stick of this shrub was bound to a bunch of hyssop by a scarlet ribbon, and the living bird was to be so attached to it, that when they dipped the branches in the water, the tail of the bird might also be moistened, but not the head nor the wings, that it might not be impeded in its flight when let loose.
lev 14:5the priest shall command that one of the birds be killed . . . over running water--As the blood of a single bird would not have been sufficient to immerse the body of another bird, it was mingled with spring water to increase the quantity necessary for the appointed sprinklings, which were to be repeated seven times, denoting a complete purification. (See Kg2 5:10; Psa 51:2; Mat 8:4; Luk 5:14). The living bird being then set free, in token of the leper's release from quarantine, the priest pronounced him clean; and this official declaration was made with all solemnity, in order that the mind of the leper might be duly impressed with a sense of the divine goodness, and that others might be satisfied they might safely hold intercourse with him. Several other purifications had to be gone through during a series of seven days, and the whole process had to be repeated on the seventh, ere he was allowed to re-enter the camp. The circumstance of a priest being employed seems to imply that instruction suitable to the newly recovered leper would be given, and that the symbolical ceremonies used in the process of cleansing leprosy would be explained. How far they were then understood we cannot tell. But we can trace some instructive analogies between the leprosy and the disease of sin, and between the rites observed in the process of cleansing leprosy and the provisions of the Gospel. The chief of these analogies is that as it was only when a leper exhibited a certain change of state that orders were given by the priest for a sacrifice, so a sinner must be in the exercise of faith and penitence ere the benefits of the gospel remedy can be enjoyed by him. The slain bird and the bird let loose are supposed to typify, the one the death, and the other the resurrection of Christ; while the sprinklings on him that had been leprous typified the requirements which led a believer to cleanse himself from all filthiness of the flesh and spirit, and to perfect his holiness in the fear of the Lord.
lev 14:10on the eighth day he shall take two he lambs without blemish, and one ewe-lamb of the first year without blemish--The purification of the leper was not completed till at the end of seven days, after the ceremonial of the birds [Lev 14:4-7] and during which, though permitted to come into the camp, he had to tarry abroad out of his tent [Lev 14:8], from which he came daily to appear at the door of the tabernacle with the offerings required. He was presented before the Lord by the priest that made him clean. And hence it has always been reckoned among pious people the first duty of a patient newly restored from a long and dangerous sickness to repair to the church to offer his thanksgiving, where his body and soul, in order to be an acceptable offering, must be presented by our great Priest, whose blood alone makes any clean. The offering was to consist of two lambs, the one was to be a sin offering, and an ephah of fine flour (two pints equals one-tenth), and one log (half pint) of oil (Lev 2:1). One of the lambs was for a trespass offering, which was necessary from the inherent sin of his nature or from his defilement of the camp by his leprosy previous to his expulsion; and it is remarkable that the blood of the trespass offering was applied exactly in the same particular manner to the extremities of the restored leper, as that of the ram in the consecration of the priests [Lev 8:23]. The parts sprinkled with this blood were then anointed with oil--a ceremony which is supposed to have borne this spiritual import: that while the blood was a token of forgiveness, the oil was an emblem of healing--as the blood of Christ justifies, the influence of the Spirit sanctifies. Of the other two lambs the one was to be a sin offering and the other a burnt offering, which had also the character of a thank offering for God's mercy in his restoration. And this was considered to make atonement "for him"; that is, it removed that ceremonial pollution which had excluded him from the enjoyment of religious ordinances, just as the atonement of Christ restores all who are cleansed through faith in His sacrifice to the privileges of the children of God.
lev 14:21if he be poor, and cannot get so much; then he shall take one lamb--a kind and considerate provision for an extension of the privilege to lepers of the poorer class. The blood of their smaller offering was to be applied in the same process of purification and they were as publicly and completely cleansed as those who brought a costlier offering (Act 10:34).
lev 14:34leprosy in a house--This law was prospective, not to come into operation till the settlement of the Israelites in Canaan. The words, "I put the leprosy," has led many to think that this plague was a judicial infliction from heaven for the sins of the owner; while others do not regard it in this light, it being common in Scripture to represent God as doing that which He only permits in His providence to be done. Assuming it to have been a natural disease, a new difficulty arises as to whether we are to consider that the house had become infected by the contagion of leprous occupiers; or that the leprosy was in the house itself. It is evident that the latter was the true state of the case, from the furniture being removed out of it on the first suspicion of disease on the walls. Some have supposed that the name of leprosy was analogically applied to it by the Hebrews, as we speak of cancer in trees when they exhibit corrosive effects similar to what the disease so named produces on the human body; while others have pronounced it a mural efflorescence or species of mildew on the wall apt to be produced in very damp situations, and which was followed by effects so injurious to health as well as to the stability of a house, particularly in warm countries, as to demand the attention of a legislator. Moses enjoined the priests to follow the same course and during the same period of time for ascertaining the true character of this disease as in human leprosy. If found leprous, the infected parts were to be removed. If afterwards there appeared a risk of the contagion spreading, the house was to be destroyed altogether and the materials removed to a distance. The stones were probably rough, unhewn stones, built up without cement in the manner now frequently used in fences and plastered over, or else laid in mortar. The oldest examples of architecture are of this character. The very same thing has to be done still with houses infected with mural salt. The stones covered with the nitrous incrustation must be removed, and if the infected wall is suffered to remain, it must be plastered all over anew.
lev 14:48the priest shall pronounce the house clean, because the plague is healed--The precautions here described show that there is great danger in warm countries from the house leprosy, which was likely to be increased by the smallness and rude architecture of the houses in the early ages of the Israelitish history. As a house could not contract any impurity in the sight of God, the "atonement" which the priest was to make for it must either have a reference to the sins of its occupants or to the ceremonial process appointed for its purification, the very same as that observed for a leprous person. This solemn declaration that it was "clean," as well as the offering made on the occasion, was admirably calculated to make known the fact, to remove apprehension from the public mind, as well as relieve the owner from the aching suspicion of dwelling in an infected house.