From a review of the new Johnny Cash album American VI: Ain’t No Grave:
The success in large part on this sixth collection, as with the entire series, comes down to song selection, which [producer Rick] Rubin has overseen with excellent taste. Talk about a dream job: Thinking up cool songs for Johnny Cash to cover. And Cash was an incredible trooper over the ten-year period that Rubin recorded him, taking on everything from country to metal to pop standards with equal alacrity. Cash only rarely refused a tune, recording over a hundred different songs for the first in the series, American Recordings, alone. (Exception: Cash wouldn’t sing “Imagine” because he couldn’t get behind John Lennon’s wouldn’t-it-be-awesome-if-no-one-believed-in-God sentiment.)
The idea of Johnny Cash refusing to sing that overplayed treacle is very appealing to me. Anyway, the album is indeed great.