The Gateless Gate, by Ekai, called Mu-mon, tr. Nyogen Senzaki and Paul Reps [1934], at sacred-texts.com

17. The Three Calls of the Emperor's Teacher

Chu, called Kokushi, the teacher of the emperor, called to his attendant: "Oshin."

Oshin answered: "Yes."

Chu repeated, to test his pupil: "Oshin."

Oshin repeated: "Yes."

Chu called: "Oshin."

Oshin answered: "Yes."

Chu said: "I ought to apologize to you for all this calling, but really you ought to apologize to me."

Mumon's comment: When old Chu called Oshin three times his tongue was rotting, but when Oshin answered three times his words were brilliant. Chu was getting decrepit and lonesome, and his method of teaching was like holding a cow's head to feed it clover.

Oshin did not trouble to show his Zen either. His satisfied stomach had no desire to feast. When the country is prosperous everyone is indolent; when the home is wealthy the children are spoiled.

Now I want to ask you: Which one should apologize?