1 Chronicles 23:28-32

From now on the assigned work of the Levites was to assist Aaron’s sons in the work of worship in GOD’s house: maintain courtyards and closets, keep the furniture and utensils of worship clean, take care of any extra work needed in the work of worship, and provide bread for the table and flour for the Meal Offerings and the unraised wafers—all baking and mixing, all measuring and weighing. Also they were to be present for morning prayers, thanking and praising GOD, for evening prayers, and at the service of Whole-Burnt-Offerings to GOD on Sabbath, at New Moons, and at all festivals. They were on regular duty to serve GOD according to their assignment and the required number. In short, the Levites, with the sons of Aaron as their companions in the ministry of holy worship, were responsible for everything that had to do with worship: the place and times and ordering of worship.