Shoyoroku - Case 7: Yakusan Ascends the Rostrum

Yakusan had not ascended the rostrum for a long time. The temple steward said,
  "All the assembly has been wishing for instruction for a long time. Please,
   Master, give your assembly a sermon."
Yakusan had the bell rung. The assembly gathered. Yakusan ascended the rostrum
and sat there for a while. Then he descended and returned to his room. The
temple steward followed him and asked,
  "You said a while ago that you would give the assembly a sermon. Why
   didn't you speak even a word?"
Yakusan said,
  "For sutras, there are sutra specialists; for sastras [1], there are
   sastra specialists. Why do you have doubts about this old monk [2] ?"

[1]: Books on Buddhist doctrines, written by ancient Buddhist philosophers.
[2]: i.e. Yakusan.