Mormon is speaking of the small plates. It is somewhat curious that he prays for their preservation, since he has included them in his own set of plates, for which he also prays preservation. However, this petition may be formulaic rather than specific. His desire is for the words of the plates to come to future generations, and perhaps Mormon foresaw that including them in his set of plates might have resulting in their being skipped—which actually seems to have happened, if the book of Mosiah immediately followed the book of Lehi in the translation sequence. Mormon is therefore praying that future generations would have the words of the small plates, not that he is concerned for the physical preservation of the plates themselves. This seems to suggest that Mormon believed that the small-plate material would be part of the record that the future translator produced.