2 Chronicles 31:16

King James 3 - The Literal Traslation

apart from their genealogy, to males from a son of three years and upward, to everyone who had gone into the house of Jehovah, the proportion of a day in its day, for their service in their duties, according to their divisions;

Cross References

1 Chronicles 23:3

And the Levites were counted from a son of thirty years and upward; and their number by their heads, as to men, thirtyeight thousand.

Ezra 3:4

They also performed the Feast of Booths, as it is written, and the burnt offerings by number, days by days, according to the ordinance, the thing of days in its day.