1 Chronicles 23:29-33

and with the showbread, and the fine flour for a grain offering, and unleavened wafers, or what is baked in the pan or what is well-mixed, and all measures of volume and size.

They are to stand every morning to thank and to praise the Lord, and likewise at evening,

and to offer all burnt offerings to the Lord, on the Sabbaths, the new moons and the appointed festivals, in the number determined by the ordinance concerning them, continually before the Lord.

So they are to perform the duties of the tent of meeting, the holy place, and of assisting the sons of Aaron their relatives, for the service of the house of the Lord.