The brass plates of Laban contained all the ancient records up to the time of Jeremiah. This includes most of the Old Testament as we now have it. It also included the works of prophets whose records are now lost—Zenoch, Zenos, and Neum. It is doubtful that they had the writings of Zephaniah, Obadiah, or Nahum. By chronology, they definitely did not have the writings of Daniel, Habakkuk, Ezekiel, Haggai, Zechariah, or Malachi. Of all these prophets, the Lord chose the last two chapters of Malachi to leave with the Nephites. However, before the Savior could introduce these passages, there was something more pressing for him to correct. They had left out an important part of their own history which most assuredly should have been recorded (see v. 9-13). This is the first priority in completing the Nephite scriptural legacy.
Hugh Nibley
"…when [the Lord] came to the Nephites he made a big thing about keeping records. He went through the records himself and made sure that all the prophecies were mentioned. Samuel the Lamanite had prophesied something that was fulfilled. You didn't put it down here, he says to Nephi. Nephi's face turned red and he said, Well, we'll see that it gets put down! (cf. 3 Nephi 23:6-13). It was very embarrassing, believe me, when the Lord himself was there! But he wants those records complete." (Temple And Cosmos, p. 321 – 322)