LotR -- Book 3 - Chapter 08 - The Road to Isengard

[Lalwendë]

"For one thing," said Theoden, "I had not heard that they spouted smoke from their mouths."

"That is not surprising," answered Merry; 'for it is an art which we have not practised for more than a few generations. It was Tobold Hornblower, of Longbottom in the Southfarthing, who first grew the true pipe-weed in his gardens, about the year 1070 according to our reckoning. How old Toby came by the plant ..."

'You do not know your danger, Theoden," interrupted Gandalf. "These hobbits will sit on the edge of ruin and discuss the pleasures of the table, or the small doings of their fathers, grandfathers, and great-grandfathers, and remoter cousins to the ninth degree, if you encourage them with undue patience. Some other time would be more fitting for the history of smoking

And another favourite bit for me is the attempted discourse on the history of smoking. This was to have been much longer but eventually found its way into the foreword, but its one of those pleasant diversions that the Hobbits often provide us with, as though Tolkien had himself stopped for a smoke at this point.