2 Chronicles 31:16
apart from their genealogy, to males from a son of three years and upward, to every one who hath gone in to the house of Jehovah, by the matter of a day in its day, for their service in their charges, according to their courses;
Ezra 3:4
And they make the feast of the booths as it is written, and the burnt-offering of the day daily in number according to the ordinance, the matter of a day in its day;
Leviticus 21:22-23
Bread of his God -- of the most holy things, and of the holy things -- he doth eat;
1 Chronicles 23:3
and the Levites are numbered from a son of thirty years and upward, and their number, by their polls, is of mighty men thirty and eight thousand.