Charles Ellicott Commentary 1 Chronicles 5:7

"And his brethren by their families, when the genealogy of their generations was reckoned: the chief, Jeiel, and Zechariah," — 1 Chronicles 5:7 (ASV)

And his brothers by their families. —“And his fellow-tribesmen, each according to his clan (Numbers 2:34), in the registration according to their genealogies, were the chief, Jeiel, and Zechariah.”

Jeiel was the chief of the second Reubenite clan, as Beerah was of the first. Zechariah and Bela were heads of the other chief houses.

It appears that these four chieftains correspond to the four divisions of Reuben mentioned in 1 Chronicles 5:3. Numbers 26:7 expressly states that “the Hanochite, the Palluite, the Hezronite, and the Carmite” were “the clans of the Reubenite.”