Numbers

Now the Levites were numbered from the age of thirty years and upward: and their number by their polls, man by man, was thirty and eight thousand.

From thirty years old and upward even until fifty years old, all that enter into the host, to do the work in the tabernacle of the congregation.

But the Levites shall pitch round about the tabernacle of testimony, that there be no wrath upon the congregation of the children of Israel: and the Levites shall keep the charge of the tabernacle of testimony.

Then David said, None ought to carry the ark of God but the Levites: for them hath the Lord chosen to carry the ark of God, and to minister unto him for ever.

These were the sons of Levi after the house of their fathers; even the chief of the fathers, as they were counted by number of names by their polls, that did the work for the service of the house of the Lord, from the age of twenty years and upward.