1 Chronicles 24:3

3 And David distributed them, that is, Sadoc of the sons of Eleazar, and Ahimelech of the sons of Ithamar, according to their courses and 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 Now these were the divisions of the sons of Aaron: The sons of Aaron: Nadab, and Abiu, and Eleazar, and Ithamar.

2 But Nadab and Abiu died before their father, and had no children: so Eleazar, and Ithamar did the office of the priesthood.

3 And David distributed them, that is, Sadoc of the sons of Eleazar, and Ahimelech of the sons of Ithamar, according to their courses and ministry.

4 And there were found many more of the sons of Eleazar among the principal men, than of the sons of Ithamar. And he divided them so, that there were of the sons of Eleazar, sixteen chief men by their families: and of the sons of Ithamar eight by their families and houses.

5 And he divided both the families one with the other by lot: for there were princes of the sanctuary, and princes of God, both of the sons of Eleazar, and of the sons of Ithamar.