I'm searching for the source of the Japanese story of a samurai spat upon which Joseph Campbell relates in The Power of Myth. (Oddly, the book has no citation on this).
. . . there is a story . . . of the samurai, the Japanese warrior, who had the duty to avenge the murder of his overlord. When he cornered the man who had murdered his overlord, and he was about to deal with him with his samurai sword, the man in the corner, in the passion of terror, spat in the warrior’s face. And the warrior sheathed the sword and walked away. [he did this] because he was made angry, and if he had killed that man in anger, then it would have been a personal act. And he had come to do another kind of act, an impersonal act of vengeance . . .
The Power of Myth, Joseph Campbell with Bill Moyers, page 75.
Does anyone know of a primary source or reference to the original source to this Japanese story or legend?
I am aware of Islamic/ Sufi stories with similar plot elements, but I'm interested in the Japanese story Campbell mentions.
I have asked a well-read friend in Japan but he is unaware of this legend. I have also searched in The Revenge of the Forty-seven Samurai - Haugaard, Erik Christian.