One evening as Shichiri Kojun was reciting sutras a thief with a sharp sword entered, demanding wither his money or his life.
Shichiri told him: “Do not disturb me. You can find the money in that drawer.” Then he resumed his recitation.
A little while afterwards he stopped and called: “Don’t take it all. I need some to pay taxes with tomorrow.”
The intruder gathered up most of the money and started to leave. “Thank a person when you receive a gift,” Shichiri added. The man thanked him and made off.
A few days afterwards the fellow was caught and confessed, among others, the offense against Shichiri. When Shichiri was called as a witness he said: “This man is no thief, at least as far as I am concerned. I gave him the money and he thanked me for it.”
After he had finished his prison term, the man went to Shichiri and became his disciple.
Source; What is a Koan? Some Music for your zazen (meditation), Tips on meditation