The Hobbit, Chapter 12

Smaug makes the rock-shadows dance with his "hot breath" (fire).

"Smaug came hurtling in from the North, licking the mountain-sides with flame, beating his great wings with a noise like a roaring wind. His hot breath shrivelled the grass before the door, and drove in through the crack they had left and scorched them as they hid. Flickering fires leaped up and black rock-shadows danced. The darkness fell as he passed again."