Looking for a story about a Zen master

This is a koan written by Japanese Zen Master Nan Yin.

Nan Yin was a famous Zen master in the Meiji period of Japan. The story of his cup of tea is often talked about and inspired by people. One day, a university professor came to ask Nan Yin for Zen. Nan Yin served him tea. He poured the tea into the visitor's cup. When the cup was full, he continued to pour the tea. The professor watched helplessly as the tea kept flowing. Overflowing out of the cup, until he could no longer remain silent, he finally said: "It's full, don't pour it out."

"Your heart is like this cup, filled with yourself "If you don't empty your cup first, how can I say Zen to you?" Nan Yin said meaningfully.