Have you considered trying to read it to him? I read
The Hobbit and about half of LOTR to my mother once. Admittedly this was when she was mostly bedridden while recovering from an auto accident, and made for a captive audience *. I'm
not suggesting you create a similar circumstance for him! 😳 But perhaps you could catch him in a receptive mood -- or if he brought up a question about an incident in the films, which you could clarify with a relevant passage.
* She enjoyed both -- especially
The Hobbit.
When I finished, she said "I like those
hobbits. I'd like to have one". 😄