Case 79: Tosu and "the Buddha's Voices"

A monk asked Tosu,
   "It is said, 'All voices are the voices of the Buddha.' Is it true or not?"
Tosu said,
   "It is true."
The monk said,
   "Master, don't fart around so loudly."
Thereupon, Tosu hit him. He asked again,
   "It is said, 'Rough words and gentle phrases return to the first principle.' 
    Is this true or not?"
Tosu said,
   "It is true."
The monk said,
   "May I call you, Master, a donkey?"
Thereupon, Tosu hit him.