C. F. Keil and Franz Delitzsch on 1 Chronicles 23:4-5

1Ch 23:4-5 1Ch 23:4 and 1Ch 23:5 contain words of David, as we learn from להלּל עשׂתי אשׁר (1Ch 23:5, end), so that we must supply דויד ויּאמר before 1Ch 23:4. מאלּה, of these (38,000) 24,000 shall be וגו לנצּח, to superintend the business, i.e., to conduct and carry on the business (the work) of the house of Jahve. This business is in 1Ch 23:28-32 more nearly defined, and embraces all the business that was to be carried on about the sanctuary, except the specifically priestly functions, the keeping of the doors, and the performance of the sacred music. For these two latter offices special sections were appointed, 4000 for the porters’ services, and the same number for the sacred music (1Ch 23:5). Besides these, 5000 men were appointed Shoterim and judges. “The instruments which I have made to sing praise” are the stringed instruments which David had introduced into the service to accompany the singing of the psalms; cf. 2Ch 29:26; Neh 12:36.