The Hobbit, or, There and Back Again
A really first-class and legendary burglar would at this point have picked the trolls' pockets – it is nearly always worth while, if you can manage it –, pinched the very mutton off the spits, purloined the beer, and walked off without their noticing him. Others more practical but with less professional pride would perhaps have stuck a dagger into each of them before they observed it. Then the night could have been spent cheerily.
Bilbo knew it. He had read a good many things he had never seen or done. He was very much alarmed, as well as disgusted; he wished himself a hundred miles away, and yet – and yet somehow he could not go straight back to Thorin and Company emptyhanded. (2.42-3)
[Gollum] was anxious to appear friendly, at any rate for the moment, and until he found out more about the sword and the hobbit, whether he was quite alone really, whether he was good to eat, and whether Gollum was really hungry. Riddles were all he could think of. Asking them, and sometimes guessing them, had been the only game he had every played with other funny creatures sitting in their holes in the long, long ago, before he lost all of his friends and was driven away, alone, and crept down, down, into the dark under the mountains. (5.22)
[Bilbo] knew, of course, that the riddle-game was sacred and of immense antiquity, and even wicked creatures were afraid to cheat when they played at it. But he felt he could not trust this slimy thing [Gollum] to keep any promise at a pinch. (5.68)