1 Chronicles 23:6

"And he appointed, according to the order of David his father, the courses of the priests to their service, and the Levites to their charges, to praise and minister before the priests, as the duty of every day required: the porters also by their courses at every gate: for so had David the man of God commanded. so had David...: Heb. so was the commandment of David the man of God"

"The sons of Levi; Gershon, Kohath, and Merari."

"And he set the Levites in the house of the LORD with cymbals, with psalteries, and with harps, according to the commandment of David, and of Gad the king's seer, and Nathan the prophet: for so was the commandment of the LORD by his prophets."

"The sons of Levi; Gershom, Kohath, and Merari."

"And they set the priests in their divisions, and the Levites in their courses, for the service of God, which is at Jerusalem; as it is written in the book of Moses. as it is...: Chaldee, according to the writing"

"So the service was prepared, and the priests stood in their place, and the Levites in their courses, according to the king's commandment."

"And Hezekiah appointed the courses of the priests and the Levites after their courses, every man according to his service, the priests and Levites for burnt offerings and for peace offerings, to minister, and to give thanks, and to praise in the gates of the tents of the LORD."

"Now these are the divisions of the sons of Aaron. The sons of Aaron; Nadab, and Abihu, Eleazar, and Ithamar."