Textual: Mormon tells us very clearly that he is selecting information out of Samuel’s prophecies. He justifies the exclusions by noting that they “cannot be written.” We do not know if the “cannot” is due to divine command or the exigencies of space and time on Mormon’s plates. This does highlight, however, the nature of the prophecies that are being written. They are not in the text to make a complete and accurate historical record. We know this because Mormon explains that this is not a complete record. What we have, therefore, are selections that Mormon has made for the specific purpose of his own text.
The last chapter contained Samuel’s prophecy of the future destruction of the Nephites. This chapter will contain the prophecies of the birth of the Messiah.