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
exo 29:1CONSECRATING THE PRIESTS AND THE ALTAR. (Exo. 29:1-35)
hallow them, to minister unto me in the priest's office--The act of inaugurating the priests was accompanied by ceremonial solemnities well calculated not only to lead the people to entertain exalted views of the office, but to impress those functionaries themselves with a profound sense of its magnitude and importance. In short, they were taught to know that the service was for them as well as for the people; and every time they engaged in a new performance of their duties, they were reminded of their personal interest in the worship, by being obliged to offer for themselves, before they were qualified to offer as the representatives of the people.
this is the thing that thou shalt do--Steps are taken at the beginning of a society, which would not be repeated when the social machine was in full motion; and Moses, at the opening of the tabernacle, was employed to discharge functions which in later periods would have been regarded as sacrilege and punished with instant death. But he acted under the special directions of God.
exo 29:4Aaron and his sons thou shalt bring unto the door of the tabernacle--as occupying the intermediate space between the court where the people stood, and the dwelling-place of Israel's king, and therefore the fittest spot for the priests being duly prepared for entrance, and the people witnessing the ceremony of inauguration.
wash them with water. And . . . take the garments--The manner in which these parts of the ceremonial were performed is minutely described, and in discovering their symbolical import, which indeed, is sufficiently plain and obvious, we have inspired authority to guide us. It signified the necessity and importance of moral purity or holiness (Isa 52:11; Joh 13:10; Co2 7:1; Pe1 3:21). In like manner, the investiture with the holy garments signified their being clothed with righteousness (Rev 19:8) and equipped as men active and well-prepared for the service of God; the anointing the high priest with oil denoted that he was to be filled with the influences of the Spirit, for the edification and delight of the church (Lev 10:7; Psa 45:7; Isa 61:1; Jo1 2:27), and as he was officially a type of Christ (Heb 7:26; Joh 3:34; also Mat 3:16; Mat 11:29).
exo 29:10And thou shalt cause a bullock to be brought before the tabernacle--This part of the ceremonial consisted of three sacrifices: (1) The sacrifice of a bullock, as a sin offering; and in rendering it, the priest was directed to put his hand upon the head of his sacrifice, expressing by that act a consciousness of personal guilt, and a wish that it might be accepted as a vicarious satisfaction. (2) The sacrifice of a ram as a burnt offering (Exo 29:15-18). The ram was to be wholly burnt, in token of the priest's dedication of himself to God and His service. The sin offering was first to be presented, and then the burnt offering; for until guilt be removed, no acceptable service can be performed. (3) There was to be a peace offering, called "the ram of consecration" (Exo 29:19-22). And there was a marked peculiarity in the manner in which this other ram was to be disposed of. The former was for the glory of God--this was for the comfort of the priest himself; and as a sign of a mutual covenant being ratified, the blood of the sacrifice was divided--part sprinkled on the altar round about, and part upon the persons and garments of the priests. Nay, the blood was, by a singular act, directed to be put upon the extremities of the body, thereby signifying that the benefits of the atonement would be applied to the whole nature of man. Moreover, the flesh of this sacrifice was to be divided, as it were, between God and the priest--part of it to be put into his hand to be waved up and down, in token of its being offered to God, and then it was to be burnt upon the altar; the other part was to be eaten by the priests at the door of the tabernacle--that feast being a symbol of communion or fellowship with God. These ceremonies, performed in the order described, showed the qualifications necessary for the priests. (See Heb 7:26-27; Heb 10:14).
exo 29:35seven days shalt thou consecrate them--The renewal of these ceremonies on the return of every day in the seven, with the intervention of a Sabbath, was a wise preparatory arrangement, in order to afford a sufficient interval for calm and devout reflection (Heb 9:1; Heb 10:1).
exo 29:36CONSECRATION OF THE ALTAR. (Exo 29:36-37)
and thou shalt cleanse the altar--The phrase, "when thou hast made an atonement for it," should be, upon it; and the purport of the direction is, that during all the time they were engaged as above from day to day in offering the appointed sacrifices, the greatest care was to be taken to keep the altar properly cleansed--to remove the ashes, and sprinkle it with the prescribed unction that, at the conclusion of the whole ceremonial, the altar itself should be consecrated as much as the ministers who were to officiate at it (Mat 23:19). It was thenceforth associated with the services of religion.
exo 29:38INSTITUTION OF DAILY SERVICE. (Exo 29:38-46)
two lambs of the first year day by day continually--The sacred preliminaries being completed, Moses was instructed in the end or design to which these preparations were subservient, namely, the worship of God; and hence the institution of the morning and evening sacrifice. The institution was so imperative, that in no circumstances was this daily oblation to be dispensed with; and the due observance of it would secure the oft-promised grace and blessing of their heavenly King.