Numbers 3:16

And Moses numbered them according to the word of the LORD, as he was commanded.

Moses numbered the Levites according to the word of the Lord, as he was commanded. The census was carried out carefully, with each tribe counted separately under census inspectors. The surrounding numbering gives definite numbers of men of a certain age, and in chapter 3 specifically records the divisions of the sons of Levi — the Gershonites, the Kohathites, and the Merarites — assigning their duties and places around the tabernacle. To the Kohathites belonged the charge to carry the ark and the sacred vessels.

That numbering and dividing established the divisions of the priests and the courses of the Levites for the service of God. Their service had to follow God's appointed order rather than human arrangements. That Mosaic order written in the book of Moses was the pattern followed when the priests were set in their divisions and the Levites in their courses for the service of God at Jerusalem at the dedication of the rebuilt temple.

The chapter shows the Aaronic priesthood was established by God's command for the Levitical dispensation, with service in the priest's office restricted to the tribe of Levi until the type met its antitype. The verse belongs to the levitical law given to the children of Israel, distinct from the law of God which is absolute and perpetual, holy, just, and good; the levitical law was abolished by Christ. This first numbering in Numbers 1-3 is to be kept for comparison with the second numbering in Numbers 26 at the close of the forty years to show how the tribes have gained and lost.