1 Chronicles 23:6-8

And David divided them into courses among the sons of Levi, {namely}, Gershon, Kohath, and Merari. {courses: Heb. divisions} Of the Gershonites {were}, Laadan, and Shimei. {Laadan: or, Libni} The sons of Laadan; the chief {was} Jehiel, and Zetham, and Joel, three.