Zhaozhou Congshen (778-897) was a disciple of Nanquan for several decades. After Nanquan passed away, Zhaozhou set out to travel to different temples throughout China to cultivate his practice further. He became a very famous Chan master and was known for the famous Koan: “Does a dog have Buddha nature?” and he replied back “Wu!” which means yes!
He has another famous Koan about tea which he uses to help bring enlightenment to students and teachers.
One morning, Zhaozhou was welcoming new arrivals.
Zhaozhou, addressing one of the monks, said, "Have you been here before?"
"Yes."
Zhaozhou replied,"Go drink tea."
Zhaozhou, addressing another monk, said, "Have you been here before?"
"No, your Reverence, this is my first visit here."
Zhaozhou replied, "Go drink tea."
The prior of the monastery took Zhaozhou to task. "One had been here before, and you gave him a cup of tea. The other had not been here, and you likewise gave him a cup of tea. What is the meaning of this?"
Zhaozhou said, "Prior!"
"Yes?" responded the prior.
"Go drink tea!"
Source: Zen’s Chinese Heritage The Masters and their Teachings by Andy Ferguson