John Gill Commentary 2 Kings 22:10

"And Shaphan the scribe told the king, saying, Hilkiah the priest hath delivered me a book. And Shaphan read it before the king." — 2 Kings 22:10 (ASV)

And Shaphan showed the king
Further related to him what follows:

saying, Hilkiah the high priest has delivered me a book ;
but did not say what book it was:

and Shaphan read it before the king ;
part of it; and it is thought by Kimchi and Ben Gersom that he particularly read the reproofs and threatenings in the book of Deuteronomy; they suppose that Hilkiah read those to Shaphan, and directed him to read them to the king, that he might take into consideration a further reformation.