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 22:2THE PRIESTS IN THEIR UNCLEANNESS. (Lev 22:1-9)
Speak unto Aaron and to his sons, that they separate themselves from the holy things--"To separate" means, in the language of the Mosaic ritual, "to abstain"; and therefore the import of this injunction is that the priests should abstain from eating that part of the sacrifices which, though belonging to their order, was to be partaken of only by such of them as were free from legal impurities.
that they profane not my holy name in those things which they hallow unto me, &c.--that is, let them not, by their want of due reverence, give occasion to profane my holy name. A careless or irreverent use of things consecrated to God tends to dishonor the name and bring disrespect on the worship of God.
lev 22:3Whosoever he be . . . that goeth unto the holy things--The multitude of minute restrictions to which the priests, from accidental defilement, were subjected, by keeping them constantly on their guard lest they should be unfit for the sacred service, tended to preserve in full exercise the feeling of awe and submission to the authority of God. The ideas of sin and duty were awakened in their breasts by every case to which either an interdict or an injunction was applied. But why enact an express statute for priests disqualified by the leprosy or polluting touch of a carcass [Lev 22:4], when a general law was already in force which excluded from society all persons in that condition? Because priests might be apt, from familiarity, to trifle with religion, and in committing irregularities or sins, to shelter themselves under the cloak of the sacred office. This law, therefore, was passed, specifying the chief forms of temporary defilement which excluded from the sanctuary, that priests might not deem themselves entitled to greater license than the rest of the people; and that so far from being in any degree exempted from the sanctions of the law, they were under greater obligations, by their priestly station, to observe it in its strict letter and its smallest enactments.
lev 22:4wash his flesh with water--Any Israelite who had contracted a defilement of such a nature as debarred him from the enjoyment of his wonted privileges, and had been legally cleansed from the disqualifying impurity, was bound to indicate his state of recovery by the immersion of his whole person in water. Although all ceremonial impurity formed a ground of exclusion, there were degrees of impurity which entailed a longer or shorter period of excommunication, and for the removal of which different rites required to be observed according to the trivial or the malignant nature of the case. A person who came inadvertently into contact with an unclean animal was rendered unclean for a specified period; and then, at the expiry of that term, he washed, in token of his recovered purity. But a leper was unclean so long as he remained subject to that disease, and on his convalescence, he also washed, not to cleanse himself, for the water was ineffectual for that purpose, but to signify that he was clean. Not a single case is recorded of a leper being restored to communion by the use of water; it served only as an outward and visible sign that such a restoration was to be made. The Book of Leviticus abounds with examples which show that in all the ceremonial washings, as uncleanness meant loss of privileges, so baptism with water indicated a restoration to those privileges. There was no exemption; for as the unclean Israelite was exiled from the congregation, so the unclean priest was disqualified from executing his sacred functions in the sanctuary; and in the case of both, the same observance was required--a formal intimation of their being readmitted to forfeited privileges was intimated by the appointed rite of baptism. If any one neglected or refused to perform the washing, he disobeyed a positive precept, and he remained in his uncleanness; he forbore to avail himself of this privilege, and was therefore said to be "cut off" from the presence of the Lord.
lev 22:8dieth of itself--The feelings of nature revolt against such food. It might have been left to the discretion of the Hebrews, who it may be supposed (like the people of all civilized nations) would have abstained from the use of it without any positive interdict. But an express precept was necessary to show them that whatever died naturally or from disease, was prohibited to them by the operation of that law which forbade them the use of any meat with its blood.
lev 22:10WHO OF THE PRIESTS' HOUSE MAY EAT OF THEM. (Lev 22:10-16)
There shall no stranger eat the holy thing--The portion of the sacrifices assigned for the support of the officiating priests was restricted to the exclusive use of his own family. A temporary guest or a hired servant was not at liberty to eat of them; but an exception was made in favor of a bought or homeborn slave, because such was a stated member of his household. On the same principle, his own daughter, who married a husband not a priest, could not eat of them. However, if a widow and childless, she was reinstated in the privileges of her father's house as before her marriage. But if she had become a mother, as her children had no right to the privileges of the priesthood, she was under a necessity of finding support for them elsewhere than under her father's roof.
lev 22:13there shall no stranger eat thereof--The interdict recorded (Lev 22:10) is repeated to show its stringency. All the Hebrews, even the nearest neighbors of the priest, the members of his family excepted, were considered strangers in this respect, so that they had no right to eat of things offered at the altar.
lev 22:14if a man eat of the holy thing unwittingly--A common Israelite might unconsciously partake of what had been offered as tithes, first-fruits, &c., and on discovering his unintentional error, he was not only to restore as much as he had used, but be fined in a fifth part more for the priests to carry into the sanctuary.
lev 22:15they shall not profane the holy things of the children of Israel--There is some difficulty felt in determining to whom "they" refers. The subject of the preceding context being occupied about the priests, it is supposed by some that this relates to them also; and the meaning then is that the whole people would incur guilt through the fault of the priests, if they should defile the sacred offerings, which they would have done had they presented them while under any defilement [CALVIN]. According to others, "the children of Israel" is the nominative in the sentence; which thus signifies, the children of Israel shall not profane or defile their offerings, by touching them or reserving any part of them, lest they incur the guilt of eating what is divinely appointed to the priests alone [CALMET].
lev 22:19THE SACRIFICES MUST BE WITHOUT BLEMISH. (Lev. 22:17-33)
Ye shall offer at your own will--rather, to your being accepted.
a male without blemish--This law (Lev 1:3) is founded on a sense of natural propriety, which required the greatest care to be taken in the selection of animals for sacrifice. The reason for this extreme caution is found in the fact that sacrifices are either an expression of praise to God for His goodness, or else they are the designed means of conciliating or retaining His favor. No victim that was not perfect in its kind could be deemed a fitting instrument for such purposes if we assume that the significance of sacrifices is derived entirely from their relation to Jehovah. Sacrifices may be likened to gifts made to a king by his subjects, and hence the reasonableness of God's strong remonstrance with the worldly-minded Jews (Mal 1:8). If the tabernacle, and subsequently the temple, were considered the palace of the great King, then the sacrifices would answer to presents as offered to a monarch on various occasions by his subjects; and in this light they would be the appropriate expressions of their feelings towards their sovereign. When a subject wished to do honor to his sovereign, to acknowledge allegiance, to appease his anger, to supplicate forgiveness, or to intercede for another, he brought a present; and all the ideas involved in sacrifices correspond to these sentiments--those of gratitude, of worship, of prayer, of confession and atonement [BIB. SAC.].
lev 22:23that mayest thou offer, &c.--The passage should be rendered thus: "if thou offer it either for a freewill offering, or for a vow, it shall not be accepted." This sacrifice being required to be "without blemish" [Lev 22:19], symbolically implied that the people of God were to dedicate themselves wholly with sincere purposes of heart, and its being required to be "perfect to be accepted" [Lev 22:21], led them typically to Him without whom no sacrifice could be offered acceptable to God.
lev 22:27it shall be seven days under the dam--Animals were not considered perfect nor good for food till the eighth day. As sacrifices are called the bread or food of God (Lev 22:25), to offer them immediately after birth, when they were unfit to be eaten, would have indicated a contempt of religion; and besides, this prohibition, as well as that contained in Lev 22:28, inculcated a lesson of humanity or tenderness to the dam, as well as secured the sacrifices from all appearance of unfeeling cruelty.