1 Chronicles 23:5 - Joseph Benson’s Commentary on the Old and New Testaments

Four thousand were porters Whose office it was to take the charge of all the gates of the temple, and its courts, that no forbidden or unclean person might enter there, and of the courts themselves, and of the several chambers and buildings belonging to the temple and the service thereof. These also were to do their work by turns. Praised the Lord with instruments Whereof two hundred and eighty-eight persons were of greater skill than their brethren, and instructed them, and had some authority over them.