The purpose of the formal consecration of the sanctuary and of the priests who served in it was, that the whole nation which Yahweh had set free from its bondage in Egypt might be consecrated in its daily life, and dwell continually in His presence as "a kingdom of priests and an holy nation." Exodus 19:6.

I will sanctify - both Aaron and his sons - So we find the sanctification by Moses according to the Divine institution was only symbolical; and that Aaron and his sons must be sanctified, i.e., made holy, by God himself before they could officiate in holy things. From this, as well as from many other things mentioned in the sacred writings, we may safely infer that no designation by man only is sufficient to qualify any person to fill the office of a minister of the sanctuary. The approbation and consecration of man have both their propriety and use, but must never be made substitutes for the unction and inspiration of the Almighty. Let holy men ordain, but let God sanctify; then we may expect that his Church shall be built up on its most holy faith.

And I will sanctify the tabernacle of the congregation, and the altar,.... This seems to intimate that something else in the preceding verse is intended, as what should be sanctified, than the tabernacle, as we supply it; or else here is a repetition of the same thing for the confirmation of it, and both that and the altar were, sanctified, or set apart for holy uses, as well as cleansed and expiated by sacrifices:

I will sanctify also both Aaron and his sons, to minister to me in the priest's office; that is, in a ceremonial way, by separating them from the rest of the children of Israel, by washing, clothing, and anointing them, and by accepting sacrifices offered by them; for this is not to be understood of internal sanctifying grace, which, though Aaron had, and many of his sons that succeeded him, yet not all; nor was it necessary to the performance of the priestly office, though it is in all those who are a royal priesthood, and made priests as well as kings unto God; for they are a holy nation, called with an holy calling, and unto himself, and have it both internally and externally.

And I will sanctify the tabernacle of the congregation, and the altar: I will sanctify also both Aaron and his sons, to minister to me in the priest's office.

29:38-46 A lamb was to be offered upon the altar every morning, and a lamb every evening. This typified the continual intercession which Christ ever lives to make for his church. Though he offered himself but once for all, that one offering thus becomes a continual offering. This also teaches us to offer to God the spiritual sacrifices of prayer and praise every day, morning and evening. Our daily devotions are the most needful of our daily works, and the most pleasant of our daily comforts. Prayer-time must be kept up as duly as meal-time. Those starve their own souls, who keep not up constant attendance on the throne of grace; constancy in religion brings in the comfort of it.