Quote Originally Posted by Kareeah_Indaga View Post
Esbern mentions it. On the way back to Delphine after digging him out of Riften IIRC.
Indeed:
Quote Originally Posted by Esbern
"Well. They've been hunting down Blades since the Great War, on general principle. But if you mean me, now, in particular... maybe they've started to get an inkling of what the return of the dragons means. I don't suppose they want the world to end any more than we do. Or at least, they'd prefer it to end on their terms."
important wording there. that is a voiced line in a main quest.