1 Chronicles 24:3
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. 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.
David set the priesthood in order by placing its administration under Zadok, of the line of Eleazar, and Ahimelech, of the line of Ithamar. Through these two men he distributed the priestly offices, assigning each priest his appointed place and work. The duties were laid out according to office in service, so that every part of the ministry had its designated workers. This careful apportioning made the whole service orderly, with no confusion but each man knowing his task.