5 And they brought that which Moses commanded before the tabernacle of the congregation: and all the congregation drew near and stood before the Lord.

6 And Moses said, This is the thing which the Lord commanded that ye should do: and the glory of the Lord shall appear unto you.

7 And Moses said unto Aaron, Go unto the altar, and offer thy sin offering, and thy burnt offering, and make an atonement for thyself, and for the people: and offer the offering of the people, and make an atonement for them; as the Lord commanded.

The people had been witnesses to the glory of God before, and in verse 6 Moses promises that they will be yet again, just as soon as Aaron has fulfilled his first priestly duties. The last time that we heard of them beholding the glory of the Lord was when they had finished the construction of the tabernacle. That had been a manifestation to the people of the Lord’s acceptance of the place, when the glory of the Lord comes again it will signify the Lord’s acceptance of the work performed therein.

This would be a key element of the Israelite faith moving forward. Miracles were shown so that those who observed them could provide testimony, could tell their children and their grandchildren that they truly knew that God was in the rituals of the tabernacle, that it was the method that He had chosen and show divine approval for. Presumably, most generations of the ancient Israelites did not get to see such signs, just as signs are rarer among us today. But the initial signs are made, and the testimony tradition begun, and history has shown that this can be enough for the pattern of faith to continue. For those that live to see signs, there is the obligation to testify of them. For those that do not, there is the obligation to believe that testimony.