1 Nephi 6

 
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Instead of writing one chapter on Lehi's genealogy (that's how long it took in Matthew 1:1-17 and Luke 3:23-38) which Joseph Smith couldn't remember or lost the notes for, we get numerous complete chapters from the book of Isaiah.

If Nephi really did need more room on his set of small plates to "write of the things of God" and bring people closer to Christ, would he really just repeat chapters written in Isaiah. Have you ever met a member of The Church of Jesus Christ of Latter-day Saints that gained their testimony of Jesus from the Isaiah chapters contained in 2 Nephi?

This is likely just an in-narrative excuse for not closely matching the 116 lost pages of the Book of Lehi (which Joseph Smith Jr. feared would turn up and be published to discredit his book, but the pages never did turn up). Notice how many times Nephi summarizes (verse 2) and says the details are not important (verse 3).

-auricularis_posterior
1 And now I, Nephi, do not give the genealogy of my fathers in this part of my record; neither at any time shall I give it after upon these plates which I am writing; for it is given in the record which has been kept by my father; wherefore, I do not write it in this work.
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2 For it sufficeth me to say that we are descendants of Joseph.
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3 And it mattereth not to me that I am particular to give a full account of all the things of my father, for they cannot be written upon these plates, for I desire the room that I may write of the things of God.
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4 For the fulness of mine intent is that I may persuade men to come unto the God of Abraham, and the God of Isaac, and the God of Jacob, and be saved.
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5 Wherefore, the things which are pleasing unto the world I do not write, but the things which are pleasing unto God and unto those who are not of the world.
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6 Wherefore, I shall give commandment unto my seed, that they shall not occupy these plates with things which are not of worth unto the children of men.
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