Numbers 4:2

Num 4:2 Take the sum of the sons of Kohath from among the sons of Levi, after their families, by the house of their fathers,

Ver. 2. Of the sons of Kohath. ] Kohath was not Levi’s firstborn, but Gershom: and yet he hath the pre-eminence, and chief charge, as of the ark, tables, candlestick, altars, &c., Num 3:31 perhaps because Moses and Aaron were of that family.