1 Chronicles 24:3

3 Then David with Zadok of the sons of Eleazar, and Ahimelech of the sons of Ithamar, divided them according to the schedule of 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 Now these are the divisions of the sons of Aaron. The sons of Aaron were Nadab, Abihu, Eleazar, and Ithamar.

2 And Nadab and Abihu died before their father, and had no children; therefore Eleazar and Ithamar ministered as priests.

3 Then David with Zadok of the sons of Eleazar, and Ahimelech of the sons of Ithamar, divided them according to the schedule of their service.

4 There were more leaders found of the sons of Eleazar than of the sons of Ithamar, and thus they were divided. Among the sons of Eleazar were sixteen heads of their fathers' houses, and eight heads of their fathers' houses among the sons of Ithamar.

5 Thus they were divided by lot, one group as another, for there were officials of the sanctuary and officials of the house of God, from the sons of Eleazar and from the sons of Ithamar.