Daniel Abraham, the creator of the comic adaptation of "A Game fo Thrones", the first book in the as-yet unifinished "A Song of Ice and Fire" fantasy series by George R. R. Martin, said in 2011 that:

"There was one scene I had to rework because there's a particular line of dialog -- and you wouldn't know it to look at -- that's important in the last scene of "A Dream of Spring [the planned seventh and final book in the series]."

(https://web.archive.org/web/20111007105040/http:/www.comicbookresources.com/?id=34496&page=article)

It has been speculated that this line has to do with Tyrion Lannister, as Anne Groell (Martin's editor) said in 2014 that Abraham "knows where Tyrion ends up".

(https://web.archive.org/web/20140604013655/http:/universe.suvudu.com/q-and-a/anne-groell)

Fans have discussed how to narrow down the line (suggesting, for example, that it is from an early part of the book), and have put forward numerous possibilities:

https://old.reddit.com/r/asoiaf/comments/8maxsm/spoilers_extended_what_god_told_abraham_about/

https://old.reddit.com/r/asoiaf/comments/ee3flw/spoilers_extended_the_throwaway_line_in_agot_that/

https://old.reddit.com/r/asoiaf/comments/j7r9bp/spoilers_extended_i_think_i_found_daniel_abrahams/

I will not resolve the market on the basis of rumours, leaks, or ambiguous comments by Martin. If it seems likely that the remaining books will never come out (even posthumously), then an announcement as to what this line would have been is sufficient to resolve this. If even that does not happen, this market will resolve N/A.