Shoyoroku - Case 2: Bodhidharma's "Vast and Void" [1]

Emperor Bu of Ryo asked Great Master Bodhidharma,
  "What is the highest meaning of the holy reality?"
Bodhidharma replied,
  "Vast and void, no holiness."
The emperor said,
  "Who are you in front of me?"
Bodhidharma said,
  "I don't know."
The emperor did not match him.

Finally, Bodhidharma crossed the Yangtse River and came to the Shorin Temple.
There he sat for nine years, facing the wall.

[1]: see case 1 of Hekiganroku.