1 Chronicles 24:2-4

New Revised Standard Version, Anglicised

² But Nadab and Abihu died before their father, and had no sons; so Eleazar and Ithamar became the priests. ³ Along with Zadok of the sons of Eleazar, and Ahimelech of the sons of Ithamar, David organized them according to the appointed duties in their service. ⁴ Since more chief men were found among the sons of Eleazar than among the sons of Ithamar, they organized them under sixteen heads of ancestral houses of the sons of Eleazar, and eight of the sons of Ithamar.