Leviticus Chapters 9-10
After Moses had help to consecrate Aaron and his sons as priests and they were required to stay in the tabernacle for seven days, it was time for their personal sacrificial offerings to inaugurate their priesthood.
On the eighth day Moses called Aaron and his sons together with the elders of Israel to provide them instructions for their individual sacrifices before the Lord. Lev. 9:1.
Moses required Aaron to take a young calf for a sin offering, and a ram for a burnt offering. Aaron also was to make a sacrifice for the people of Israel as a part of his sacrificial ceremony, and be prepared to witness the appearance of glory of the Lord.
The sacrificial animals were delivered to Aaron and the people of Israel gathered to observe. Lev. 9:2-6.
Aaron specifically followed Moses’ instruction for the sacrifices including the sin offering and the burnt offerings involving the various parts of the sacrificed animals. The animals’ blood was sprinkled at the altar. The flesh and the hide of the animals were removed from the tabernacle and disposed. Lev. 9:7-11.
Aaron, assisted by his sons, prepared the animals and the other meal offerings of the people, and performed the sacrifices as instructed. Lev. 9:12-21.
When he finished, Aaron lifted up his hand to bless the people. He and Moses then went into the tabernacle of the congregation and came out and blessed the people and "the glory of the Lord appeared unto all the people. And there came a fire out from before the Lord and consumed upon the altar the burnt offering". When the people witnessed the event, they "shouted, and fell on their faces." Lev. 9:24.
Two sons of Aaron, Nadab and Abihu, then committed a sin by attempting an unauthorized sacrifice. They took "censers" (flat pans) and made a fire on the censers to burn incense, creating a "strange fire before the Lord" which was not authorized by the Lord’s specific instructions or from Moses. Lev. 10:1. In addition, the two apparently were intoxicated at the time. . See Lev. 10:9.
When this "strange fire" occurred, "there went out fire from the Lord, and devoured them" and they died. Lev. 10:2.
Aaron would have obviously been upset over the death of his sons, but Moses reminded him that the Lord is to be glorified according to his specific instructions Moses commanded two of Aaron’s nephews to come and carry their cousins out of the tabernacle in their coats for burial outside the tabernacle. Lev. 10:3-5. Moses instructed Aaron not to grieve, but to let the people of Israel cry out and morn and review the Lord’s action in the burning of the two sinning sons. Moses told Aaron not to leave the tabernacle. Lev. 10:6-7.
The lord then instructed Aaron and his remaining sons never to enter the tabernacle after intoxicating drink; further instructing Aaron to keep separate, in sacrifices to the Lord, clean from unclean, and holy from unholy. Lev. 10:8-11.
Moses then instructed Aaron’s remaining two sons Eleazar and Ithamar, specifically on sacrifices regarding their proper consumption of part of the sacrifices. The sacrifices apparently were carried out properly, but the sons did not eat of the portion to which they were allowed. Moses at first was angry at their not eating, but Aaron explained that the events of the day in his loss of two other sons, had apparently left him skeptical; and Moses understood and was then content with their actions. Lev. 10:12-20.