"He is here." Gandalf murmured as he crossed the room, with Bilbo behind him and went to open the door. On the doorstep stood a dwarf with hair as black as the other dwarf who had come with his twin earlier, and silver-grey eyes that seemed to bore straight into your soul. He glowered up at the wizard as he stepped over the threshold. 
"Gandalf. I thought you said this place would be easy to find; I lost my way, twice. Wouldn't have found it at all if it hadn't been for that mark on the door."

"Mark on the d-?!" Bilbo gawked at the dwarf in shock, then protested indignantly. "There is no mark on that door, I assure you sir, it was painted just last week!"
"There is a mark, Bilbo. I put it there myself." the wizard confessed.