The great mystery contained on the 24 plates includes the Book of Ether. Moroni said, I take mine account from the twenty and four plates which were found by the people of Limhi, which is called the Book of Ether (Ether 1:2). But Moroni abridged the record and did not include all of the prophecies of the brother of Jared. They were withheld because of their greatness, for the Lord showed unto the brother of Jared all the inhabitants of the earth which had been, and also all that would be (Ether 3:25). This great revelation is to come forth when the people are ready, in that day that they shall exercise faith in me, saith the Lord even as the brother of Jared did, that they may become sanctified in me, then will I manifest unto them the things which the brother of Jared saw, even to the unfolding unto them all my revelations (Ether 4:7).
Mosiah 9 The Record of Zeniff
Mormon inserts this history of the people of Zeniff. It comprises about 70 years and three kings, Zeniff, Noah, and Limhi. It is important to remember that chronologically this is a flashback—to tell us what happened to these people and give background for the state of affairs with Limhi’s people. This record includes chapters 9-22 and is taken from the plates spoken of in Mosiah 8:5.