Nehemiah 12:45

Overview - Nehemiah 12
The priests and the Levites which came up with Zerubbabel.
10 The succession of high priests.
22 Certain chief Levites.
27 The solemnity of the dedication of the walls.
44 The offices of priests and Levites appointed in the temple.
Treasury of Scripture Knowledge

Nehemiah 12:45  (King James Version)
And both the singers and the porters kept the ward of their God, and the ward of the purification, according to the commandment of David, and of Solomon his son.

the singers
1 Chronicles 25:1-26:32

the ward
That is, they suffered no unclean person to enter the temple.
1 Chronicles 23:28 ; 2 Chronicles 23:6