The Zen master Mu-nan had only one successor. His name was Shoju. After Shoju had completed his study of Zen, Mu-nan called him into his room. "I am getting old," he said, "and as far as I know, Shoju, you are the only one who will carry on this teaching. Here is a book. It has been passed down from master to master for seven generations. I have also added many points according to my understanding. The book is very valuable, and I am giving it to you to represent your successorhip."
"If the book is such an important thing, you had better keep it," Shoju replied. "I received your Zen without writing and am satisfied with it as it is."
"I know that," said Mu-nan. "Even so, this work has been carried from master to master for seven generations, so you may keep it as a symbol of having received the teaching. Here."
They happened to be talking before a brazier. The instant Shoju felt the book in his hands he thrust it into the flaming coals. He had no lust for possessions. Mu-nan, who never had been angry before, yelled: "What are you doing!" Shoju shouted back: "What are you saying!"
Source: Zen Flesh, Zen Bones