"Honor pursues him who tries to escape it." Moses in his humility felt that his mission as leader of the people ended with the erection of the Tabernacle, as Israel could now satisfy all their spiritual needs without his aid. But God said: "As truly as thou livest, I have for thee a far greater task than any thou hast yet accomplished, for thou shalt instruct My children about 'clean and unclean,' and shalt teach them how to offer up offerings to Me." God hereupon called Moses to the Tabernacle, to reveal to him there the laws and teachings.  Moses in his humility did not dare to enter the Tabernacle, so that God had to summon him to enter. Moses, however, could not enter the sanctuary while a cloud was upon it, this being a sign "that the demons held sway," but waited until the cloud had moved on. The voice that called Moses came from heaven in the form of a tube of fire and rested over the two Cherubim, whence Moses perceived its sound. This voice was a powerful as at the revelation at Sinai when the souls of all Israel escaped in terror, still it was audible to none but Moses. Not even the angels heard it, for the words of God were destined exclusively for Moses. Aaron, too, with the exception of three cases in which God revealed Himself to him, never received His commands except through the communications of Moses. God would call Moses twice caressingly words by name, and when he had answered, "Here am I," God's words were revealed to him, and every commandment as a special revelation. God always allowed a pause to take place between the different laws to be imparted, that Moses might have time rightly to grasp what was told him. 
On the first day of the dedication of the Tabernacle, not lest than eight important sections of laws were communicated to Moses by God.  As a reward for his piety, Aaron and his descendants to all eternity received the laws of sanctity, which are a special distinction of the priests,  and these laws were revealed on this day. It was on this day, also, that Aaron and his sons received the gifts of the priests, for although even at the revelation on Sinai Israel had set them aside, still they were not given to Aaron and his sons until this day when the sanctuary was anointed. 
The second law revealed on this day was the separation of the Levites from among the children of Israel, that they might be dedicated to the sanctuary. "For God elevated no man to an office unless He has tried him and found him worthy of his calling." He did not say, "and the Levites shall be Mine," before He had tried this tribe, and found them worthy. In Egypt none but the tribe of Levi observed the Torah and clung to the token of the Abrahamic covenant, while the others tribes, abandoning both Torah and token of covenant, like the Egyptians, practiced idolatry. In the desert, also, it was this tribe alone that did not take part in the worship of the Golden Calf. Justly, therefore, did God's choice fall upon this godly tribe, who on this day were consecrated as the servants of God and His sanctuary. 
The ceremonies connected with the consecration of the Levites had much in common with the regulations for cleansing of lepers. Originally, the firstborn had been the servants of the sanctuary, but, owing to the worship of the Golden Calf, they lost this prerogative, and the Levites replaced them. It was for this reason that the Levites were obliged to observe regulations similar to those for the cleansing of lepers, because they took the place of men who by their sins had defiled themselves. The offerings that the Levites brought on this occasion consisted of two bullocks, on for a burnt offering whenever the congregation, seduced by others, commits idolatry; and Israel would not have worshipped the Golden Calf had not the mixed multitude misled them. "But whosoever worships an idol, by this act renounces the whole Torah," hence did the Levites have to offer up another bullock for a sin offering, in accordance with the law that "if the whole congregation of Israel have done somewhat against any of the commandments of the Lord concerning things which should not be done, and are guilty, then they shall offer up a young bullock for the sin." As the Levites had been chosen "to do the service of the children of Israel in the Tabernacle of the congregation, and to make an atonement for the children of Israel," God ordered all the congregation of Israel to be present at the consecration of the Levites, for whosoever had a sin offering up for himself must in person bring it to the Tabernacle. Therefore, too, did the elders of Israel have to put their hands upon the Levites, according to the prescription that the elders must put their hands upon the sin of the congregation. Aaron, like the elders, participated in the ceremony of the consecration, lifting up every single Levite as a token that he was now dedicated to the sanctuary.  Aaron's extraordinary strength is proven by the fact that he was able to lift up twenty-tow thousand men in one day.