And Shemaiah the son of Nethaneel the scribe, one of the Levites, wrote them before the king, and the princes, and Zadok the priest, and Ahimelech the son of Abiathar, and before the chief of the fathers of the priests and Levites: one principal household being taken for Eleazar, and one taken for Ithamar. And Shemaiah - "Moses the great scribe, who is called Shemaiah, the son of Nethaneel, of the tribe of Levi, wrote them down." - T.
One principal household - for Eleazar - The family of Eleazar was the most illustrious of the sacerdotal families, because Eleazar was the first-born of Aaron, Ithamar's family was the second in order and dignity; therefore one of the principal families of Eleazar was first taken, and then one of Ithamar's, and thus alternately till the whole was finished.