Nehemiah 12:45

And both the singers and the porters kept the ward of their
God, and the ward of their purification
The singers kept their turns in course in the temple, and were not wanting to officiate on all occasions, besides morning and evening services; and the porters they diligently kept the gates of the temple, that no impure person or thing in a ceremonial sense entered:

according to the commandment of David, and Solomon his son;
who made very good rules and orders relative to the better and more regular performance of service by them; see ( 1 Chronicles 25:1 ) ( 26:1 ) ( 2 Chronicles 8:14 ) .