An explanation of the Koan answer
It's a quite conventional Koan. The master is asked: What is Buddha? This question is identical to What is Zen? What is enlightenment? etc.
There's no answer to these issues that can be expressed in words.
Therefore every answer to this kind of Koans is right.
But here's a master who says something.
His answer has to be repeated to come closer to enlightenment yourself. Hm.
The background story of this Koan
This Koan refers to everyday life in an old Chinese Zen monastery. Nobody had no toilet paper in those days. How did they remove the remaining shit from their bottom?
Until today millions of Indians use their left hand. It's washed after the procedure. But until today for eating, Indians only use their right hand.
Chinese didn't use their hand but had sticks for both situations.
Chopsticks for eating are well known around the world.
The stick on the toilet to scrape the bottom is less known and hardly used any more. It was a shameful hidden "tool", one can imagine. No one would speak about it.
To make this stick a representation of the Buddha shows madness. That's what enlightenment is, Zen proclaims.
Traditional Commentaries and .... Poems (Gata)
It seems to me Ummon is so poor he cannot distinguish the taste of one food from another, or else he is too busy to write readable letters.
Well, he tried to hold his school with dried dung. And his teaching was just as useless.
Yunmen may name it, but a poor family has difficulty preparing simple food, and a hurried business is inadequate grass writing.
He moved to relieve himself by using a “shit scraper” next to prop up the gate and hang the doors.
One can see the Buddha Dharma waxes and wanes.