1 Chronicles 24:3

3 And David distributed them, Zadok being of the sons of Eleazar, and Ahimelech of the sons of Ithamar, according to their turns in their ministry.

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 sons of Aaron also had their courses. The sons of Aaron: Nadab, Abihu, Eleazar, and Ithamar.

2 But Nadab and Abihu died before their father and had no children; therefore, Eleazar and Ithamar had the priesthood.

3 And David distributed them, Zadok being of the sons of Eleazar, and Ahimelech of the sons of Ithamar, according to their turns in their ministry.

4 And there were more men found of the sons of Eleazar than of the sons of Ithamar, and thus were they divided. Among the sons of Eleazar, there were sixteen chief men of the houses of their fathers and eight among the sons of Ithamar according to the houses of their fathers.

5 They divided them, therefore, by lot, one with another for of the sons of Eleazar and of the sons of Ithamar there were princes of the sanctuary and princes of God.