1 Chronicles 23:28
Because 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, and the work of the service of the house of God; Because 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, and the work of the service of the house of God;
The verse stands in chapters 21-23 at the close of David's prosperous reign. Those last chapters establish the worship of God under David, prepare for the building of the temple, and bring Solomon to the throne under special divine blessing. The service of the house of the Lord is part of that Davidic organization of worship, whose magnificence is shown by the treasure prepared for Solomon's temple, amounting in round numbers to $2,843,740,000 in gold and $1,670,422,000 in silver for a total of $4,514,000,000, besides vast amounts of brass, iron, copper, and precious stones.
The verse sets forth the hereditary duty of the Levites to serve the sons of Aaron in the service of the house of God. The genealogies and service assignments in Chronicles provided the records needed after the exile so the land could be assigned to its hereditary owners and the temple service could be taken up again by the families whose hereditary duty it was. Priests and Levites were distinctly separated in office, with offices in no sense similar or interchangeable, and the Levites were the priests' appointed servants to do the manual work of the service of the house of God. Their office to wait on the sons of Aaron meant providing the showbread, making ready the meat offering, baking the unleavened cakes, and cleansing from day to day the courts and chambers of the Lord's house and all its vessels. During the national morning and evening sacrifice offered by the priests, the Levites stood by to offer the formal words of praise and thanksgiving, and at all the set feasts, such as the new moon and the Sabbaths, they burned the sacrifices to any number as ordered by the priests.
After the temple was built the Levites were given the work of waiting on the priests in the sanctuary service, including preparing the showbread, often leading the singing, collecting the tithe, and doing a large amount of other work connected with the service. In the time of David they entered this sanctuary service at twenty years of age, and at fifty years of age they returned from the warfare of the service, no longer expected to perform arduous duties while still retaining charge of the work. Their work was largely confined to the court and typifies the work of the gospel ministry of the present day.