Matthew Poole and continuators on 1 Chronicles 23:5

5 Moreover, four thousand were porters , and four thousand praised the LORD with instruments which I made (said David) to praise therewith.

Whose Office 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 several Chambers or Buildings belonging to the Temple and the Service thereof. These also were to do their Work by turns.

Whereof 288 were persons of greater skill than their Brethren, and did Instruct them, and had some Authority over them.