Nehemiah 12:46 - Joseph Benson’s Commentary on the Old and New Testaments

For in the days of David, &c. This verse gives the reason why the Levites and the singers performed their duty so accurately; because, from the time of David, who constituted their orders and offices, there were overseers appointed, who presided over them, and were careful both to instruct them in their duty, and keep them to it.