1 Chronicles 24:1-3

King James Version

24 Now these are the divisions of the sons of Aaron. The sons of Aaron; Nadab, and Abihu, Eleazar, and Ithamar.

² But Nadab and Abihu died before their father, and had no children: therefore Eleazar and Ithamar executed the priest's office.

³ And David distributed them, both Zadok of the sons of Eleazar, and Ahimelech of the sons of Ithamar, according to their offices in their service.