Where chapter 8 prepares Aaron to be able to be able to start the priestly duties, chapter 9 kicks off Aaron’s first duties in office. After a full week of continual sacrifice to prepare Aaron and the tabernacle/altars for full time service (these are the purification (sin offerings) and burnt offerings), the eighth day arrives. The work that is to be done points to the whole reason any of this is going on, worship of God and the desire for His glory (think presence) to be revealed to them.
Different sacrifices/animals are represented for different parties. Moses tells Aaron to a bull calf for a purification offering for the altar/tabernacle and a ram for a burnt offering (for his personal atonement). There is no shortage of irony here that Aaron’s first duty as the official high priest is to sacrifice a young calf, the same animal that he made a golden image of and declared to be Yahweh in Moses’ absence. The people of Israel (again, likely represented by the elders) are instructed to bring a male goat for there purification (sin) offering and a calf and a lamb for their burnt offerings. Also, they are to bring an ox and a lamb for the peace offering as well as the grain and oil.
Everyone agrees and does what they are supposed to. Moses twice tells them that the result of all of this will be the glory of the Lord will appear to them. Again, these sacrifices help to bring the tabernacle to purity (defiled by the people and their sin but cleansed so that they can approach for atonement for their sin) as well as to allow for that atonement that restores right relationship between man and God. What was the glory of God that would appear? It’s likely the pillars of cloud/fire that had been present many times in the past. Sacrifices at the tabernacle were of no use if Yahweh was not there, His presence made the entire thing work. What is happening on this day is the initiation what will need to be in place for all of this to keep working.
The wide variety of animals is likely intentional, Aaron gets a chance to do all but one of the sacrifices (the reparation offering from chapter 5, that’s a specific situation that isn’t occurring here). Broadly, we should see these atonement for the general sinfulness of the nation, to dedicate the whole people to the worship of God according to his means, and to pray for God’s blessing on them. Then Moses and Aaron go into the tent of meeting and come out and bless the people. The Lord validates this blessing by appearing and then consuming the already burning offerings with fire. The people, as you would expect, give a shout and fall on their faces.
What can we take away from this? It puts all of the ceremony into context. All of this is pointing to something, ultimately the proper worship of God. The elaborate dress of the priests, the procedures around the sacrifices, etc. all helped simple human minds appreciate the holiness of God. None of it ensures God’s presence, He gives that graciously, but it provides a window into how to understand the presence that they are asking for. There are also aspects of spontaneous praise as well as fear in reaction to the God’s presence. This is difficult for us as often our worship is manufactured. Perhaps a pillar of fire would straighten that right out.