Mosiah 28

I find it interesting that Mormon, with no explanation tells us that king Mosiah  -

"...took the plates of brass, and all the things which he had kept, and conferred them upon Alma, who was the son of Alma; yea, all the records, and also the interpreters, and conferred them upon him, and commanded him that he should keep and preserve them, and also keep a record of the people, handing them down from one generation to another, even as they had been handed down from the time that Lehi left Jerusalem."  (Mosiah 28:20)

Maybe because -

"...not any of his sons who would accept of the kingdom."  (Mosiah 28:10)

...and he knew that the kingship was about to end.