1 Chronicles 24:1

And Aaron took Elisheba, the daughter of Amminadab, the sister of Nahshon, as a wife, and she bore him Nadab and Abihu, Eleazar and Ithamar.

also for the divisions of the priests and the Levites and for all the work of the service of the house of Yahweh and for all the utensils of service in the house of Yahweh;

Now it happened that when the priests came out of the holy place (for all the priests who were present had sanctified themselves, without regard to divisions),

And according to the judgment of his father David, he caused the divisions of the priests to stand for their service, and the Levites for their responsibilities to praise and minister before the priests according to the daily rule, and the gatekeepers by their divisions at every gate; for David the man of God had so commanded.

So the Levites and all Judah did according to all that Jehoiada the priest commanded. And each one of them took his men who were to come in on the sabbath, with those who were to go out on the sabbath, for Jehoiada the priest did not dismiss any of the divisions.

And Hezekiah set up the divisions of the priests and the Levites by their divisions, each according to his service, both the priests and the Levites, for burnt offerings and for peace offerings, to minister and to give thanks and to praise in the gates of the camp of Yahweh.

Then they appointed the priests to their sections and the Levites in their divisions for the service of God in Jerusalem, as it is written in the book of Moses.

Divisions of Levites