The Hobbit, or, There and Back Again
Now a nasty suspicion began to grow in his mind – had the dwarves forgotten this important point [about transportation of Bilbo's gold back to Bag-End] too, or were they laughing in their sleeves at him all the time? That is the effect that dragon-talk has on the inexperienced. Bilbo of course ought to have been on his guard; but Smaug had rather an overwhelming personality. (12.68)
So Bilbo told them all he could remember, and he confessed that he had a nasty feeling that the dragon guessed too much from his riddles added to the camps and the ponies. [...]
"Well, well! It cannot be helped and it is difficult not to slip in talking to a dragon, or so I have always heard," said Balin anxious to comfort him. "I think you did very well, if you ask me – you found out one very useful thing at any rate, and got home alive, and that is more than most can say who have had words with the likes of Smaug." (12.86-7)
The Elvenking looked at Bilbo with a new wonder. "Bilbo Baggins!" he said. "You are more worthy to wear the armour of elf-princes than many that have looked more comely in it. But I wonder if Thorin Oakenshield will see it so. I have more knowledge of dwarves in general than you have perhaps. I advise you to remain with us, and here you shall be honoured and thrice welcome."
"Thank you very much I am sure," said Bilbo with a bow. "But I don't think I ought to leave my friends like this, after all we have gone through together. And I promised to wake old Bombur at midnight, too! Really, I must be going, and quickly." (16.41)