He began abridging after Omni and abridged five books, and didn't finish his own, having been killed in battle partway through his own chapter, and the record being given to his son.
So Moroni finished his father's chapter (Mormon) and then also abridged Ether, and then finished with his own book.
But the one that somehow escaped my attention was that Nephi abridged Lehi's work:
17 But I shall make an account of my proceedings in my days. Behold, I make an abridgment of the record of my father, upon plates which I have made with mine own hands; wherefore, after I have abridged the record of my father then will I make an account of mine own life.
(1 Nephi 1)
But abridging and summarizing work isn't a new practice that began with Nephi.
Genesis isn't a first-hand account, it is a summary or recount or abridgement given by Moses as a restorer of Israel, of the creation. Not sure where he got his information, either by urim and thummim, or off another record, but it's interesting of the records we have, the earliest that's been handed down to us comes from a restorer - Moses a few thousand years after the creation. We didn't receive the original record from Adam but through a restorer.
So the Book of Mormon concept isn't a new concept where a restorer summarizes and catches everybody up or gives what we need to know to us. But there's also a spiritual principle that's laid out in the scriptures on this in terms of summarizing and what's to be presented and shared by the servants of the Lord:
9 ...It is given unto many to know the mysteries of God; nevertheless they are laid under a strict command that they shall not impart only according to the portion of his word which he doth grant unto the children of men, according to the heed and diligence which they give unto him.
10 And therefore, he that will harden his heart, the same receiveth the lesser portion of the word; and he that will not harden his heart, to him is given the greater portion of the word, until it is given unto him to know the mysteries of God until he know them in full.
11 And they that will harden their hearts, to them is given the lesser portion of the word until they know nothing concerning his mysteries; and then they are taken captive by the devil, and led by his will down to destruction. Now this is what is meant by the chains of hell. (Alma 12).
There were many times in the Book of Mormon where the prophets were counseled not to share what was revealed to them - and this practice is also given to us in the temples, and with special blessings we are given.
At any rate, thought for the day while I was reading the scriptures.