When a rebel army took over a Korean town, all fled the Zen temple except the abbot. The rebel general burst into the temple, and was incensed to find that the master refused to greet him, let alone receive him as a conqueror.
“Don’t you know,” shouted the general, “that you are looking at one who can run you through without batting an eye?”
“And you,” said the abbot, “are looking at one who can be run through without batting an eye.”
The general’s scowl turned into a smile. He bowed low and left the temple.

(Other Authors and Sources)

Zen Koan

In Lucien Stryk, Takashi Ikemoto, and Taigan Takayama, Zen Poems of China and Japan: The Crane's Bill (1973)