John Gill Commentary Exodus 6:17

"The sons of Gershon: Libni and Shimei, according to their families." — Exodus 6:17 (ASV)

And the sons of Gershom, Libni, and Shimi, according to their families He had only two sons, from whom came the families of the Libnites and Shimites; see (Numbers 3:21) .