These were the sons of Levi by name: Gershon, Kohath, and Merari.
17. And these were the sons of Levi by their names Hence it appears that the tribe of Levi, like the others, had made an astonishing progress from a small and contemptible beginning; for whereas he himself had only begotten three sons, Gershon and Merari only two each, and Kohath four; who would have expected such an increase, that twelve men in so short a...
The Levites being granted to Aaron to minister to him, they are here delivered to him by tale, that he might know what he had, and employ them accordingly. Observe, I. By what rule they were numbered: Every male from a month old and upward, Num 3:15.
Commenting on Numbers 3:14-39
And these were the sons of Levi, by their names,.... The immediate offspring and descendants of that patriarch: Gershon, and Kohath, and Merari; these went down with him into Egypt, Gen 46:11.