Numbers 3:19

The sons of Gershon: Libni and Shimei, according to their families.

The sons of Kohath: Amram and Izhar and Hebron and Uzziel; and the years of Kohath’s life were 133 years.

The Levites, however, were not numbered among them by their fathers’ tribe.

Then the Levites arose: Mahath, the son of Amasai and Joel the son of Azariah, from the sons of the Kohathites; and from the sons of Merari, Kish the son of Abdi and Azariah the son of Jehallelel; and from the Gershonites, Joah the son of Zimmah and Eden the son of Joah;

“Yet they shall be ministers in My sanctuary, having oversight at the gates of the house and ministering in the house; they shall slaughter the burnt offering and the sacrifice for the people, and they shall stand before them to minister to them.