1 Chronicles 23:27-29

27For by the last words of David the sons of Levi were numbered, from twenty years old and upward.

28For their office was to wait on the sons of Aaron for the service of the house of the LORD, in the courts, and in the chambers, and in the purifying of all holy things, even the work of the service of the house of God;

29for the shewbread also, and for the fine flour for a meal offering, whether of unleavened wafers, or of that which is baked in the pan, or of that which is soaked, and for all manner of measure and size;