1 Chronicles 24:3

3 And David, with Zadok of the sons of Eleazar and Ahimelech of the sons of Ithamar, divided them according to their appointments for 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 And as for the sons of Aaron, [these were] their divisions. The sons of Aaron [were] Nadab and Abihu, Eleazar and Ithamar.

2 And Nadab and Abihu died before their father, and {they had no sons}, so Eleazar and Ithamar served as priests.

3 And David, with Zadok of the sons of Eleazar and Ahimelech of the sons of Ithamar, divided them according to their appointments for their service.

4 And more sons of Eleazar were found as heads of the men than the sons of Ithamar, so they divided them to the sons of Eleazar [to be] sixteen heads over the house of the fathers, and to the sons of Ithamar over the house of the fathers [were] eight [heads].

5 They divided them by lot {all alike}, for they were commanders of the sanctuary and commanders of God from among the sons of Eleazar and the sons of Ithamar.