Numbers 8:1-13 The Lord instructed Moses to instruct Aaron on how to set up the lamps in front of the lampstand to light it up. Aaron cleansed the Levites for duty by shaving, washing, and sacrificing.
Notes: the seven lamps … give light in front of the lampstand, that is, that their light shines on the table opposite it in the tabernacle (see The Tabernacle Tent) on which are 12 flat loaves of bread symbolizing the 12 tribes of Israel (Ex. 25:23–30). Light reflects the glorious presence of God, so this arrangement of the furniture in the tabernacle is a reminder of God’s ongoing intention to bless the people of Israel
Numbers 8:14-19 The Levites were not officially set apart for God for service instead of all those of Israel who first open the womb in birth. The Levites were a gift to Aaron for the Priesthood in their service for caring for the tabernacle to make atonement for the children of Israel so no plague would come to them if they come to close to the sanctuary.
Notes: The ceremony was completed by offering two sacrifices (the burnt and sin offering) using bulls, the most valuable of sacrificial animals.
Numbers 8:20-26 Moses and Aaron did all the Lord commanded concerning the Levites, and then the Levites began their service. All those Levites 25 years old and upward to 50 years old will serve. Over 50 years old, they shall instead service their brother Levites by keeping guard over their duties.
Notes: At age 50 Levites were to retire from the duty of the service (i.e., the work involved in transporting the tabernacle) because carrying the tabernacle was too hard for older men.