1 Chronicles 24:3

3 David with Tzadok of the sons of El`azar, and Achimelekh of the sons of Itamar, divided them according to their ordering in their service.

1 Chronicles 24:3 Meaning and Commentary

1 Chronicles 24:3

And David distributed them
The posterities of Eleazar and Ithamar into certain classes or courses:

both Zadok of the sons of Eleazar, and Ahimelech of the sons of
Ithamar;
these were the two principal men of the respective families, the one was high priest, and the other "sagan" or deputy; or they both officiated as high priests alternately, until the one was removed in Solomon's time, and the other established alone. And now their brethren the priests, who were under each of these, are the persons David divided into classes:

according to their offices in their service:
to perform their office as priests in the service of the temple in their turns.

1 Chronicles 24:3 In-Context

1 The courses of the sons of Aharon [were these]. The sons of Aharon: Nadav and Avihu, El`azar and Itamar.

2 But Nadav and Avihu died before their father, and had no children: therefore El`azar and Itamar executed the Kohen's office.

3 David with Tzadok of the sons of El`azar, and Achimelekh of the sons of Itamar, divided them according to their ordering in their service.

4 There were more chief men found of the sons of El`azar than of the sons of Itamar; and [thus] were they divided: of the sons of El`azar there were sixteen, heads of fathers' houses; and of the sons of Itamar, according to their fathers' houses, eight.

5 Thus were they divided by lot, one sort with another; for there were princes of the sanctuary, and princes of God, both of the sons of El`azar, and of the sons of Itamar.