1 Chronicles 24:1-4

These were the groups of Aaron’s sons: Aaron’s sons were Nadab, Abihu, Eleazar, and Ithamar. But Nadab and Abihu died before their father did, and they had no sons. So Eleazar and Ithamar served as the priests. David, with the help of Zadok, a descendant of Eleazar, and Ahimelech, a descendant of Ithamar, separated their family groups into two different groups. Each group had certain duties. There were more leaders from Eleazar’s family than from Ithamar’s—sixteen leaders from Eleazar’s family and eight leaders from Ithamar’s family.