Numbers 3:19

And these were the sons of Levi by their names; Gershon, and Kohath, and Merari.

And these are the names of the sons of Gershon by their families; Libni, and Shimei.

And the sons of Merari by their families; Mahli, and Mushi. These are the families of the Levites according to the house of their fathers.

Of Gershon was the family of the Libnites, and the family of the Shimites: these are the families of the Gershonites.