1 Chronicles 23:5
Moreover four thousand were porters; and four thousand praised the LORD with the instruments which I made, said David, to praise therewith. Moreover four thousand were porters; and four thousand praised the LORD with the instruments which I made, said David, to praise therewith.
In its setting the verse records part of David's carefully studied apportioning of special duties to the men best fitted for them. This apportioning was studied by David in his government of Israel and was perfected in his organization of priests and Levites, civil officers, and army as Solomon was placed on the throne. The four thousand porters and four thousand musicians were part of 38,000 Levites numbered from thirty years old and upward. Of that number 24,000 were to set forward the work of the house of the Lord, 6,000 were officers and judges, 4,000 were porters, and 4,000 praised the Lord with the instruments David made. The porters' work was definitely arranged.
The four thousand who praised with the instruments David made were divided into twenty-four courses. Each course was led by twelve men especially instructed and skilful in the use of musical instruments.