Story of Hui Neng, the Sixth Patriarch

One day, Hong Ren (Hung-jen), the fifth patriarch, called his disciples together and instructed them: "Each of you write a verse and bring it to me. I will read your verses, and if there is one who is awakened to the cardinal meaning, I will give him the robe and the Dhama and make him the Sixth Patriarch. Hurry, Hurry!"
The disciples returned to their cells, overwhelmed by the master's request. They agreed to let the first among them, Shen Xiu (Shen-hsiu), take on the task of composing a verse. Though well-instructed in the sutras, Shen Xiu was still far from enlightenment and the master's instructions threw him into a deep anxiety. At length he produced his verses and at midnight wrote on the middle wall of the south hall:
The body is the Bondhi tree,
The mind is like a clear mirror.
At all times we must strive to polish it.
And must not let the dust collect.
Master Hong Ren was the first to see the verses the next morning. Assembling of the monks, he burned incense before the inscription on the wall. The disciples were filled with wonder and consider the question of succession settled. The master, however, called Shen Xiu aside. Having confirmed his suspicion that Shen Xiu had written the verses, the master said to him: "The verse you wrote shows that you still have not reached true understanding. You have merely arrived at the front of the gate but have yet to be able to enter it." As the verses make evident, practice can help ordinary persons, but it cannot bring them to perfect enlightenment. "You must enter the gate and see your own original nature..."
He left Shen Xiu to compose further verses. Days passes, but the first monk of the community could not produce a sign of his enlightenment.
Hui Neng, a young monk, heard about the verse and immediately realized that it did not express enlightenment. He formulated a new verse and have it posted on the wall of the west hall:
Originally there is no tree of enlightnment,
Nor is there a stand with a clear mirror.
From the beginning not one thing exists;
Where, then, is a grain of dust to cling?
At midnight, Hong Ren summoned Hui Neng and conferred on him the Dharma of Sudden Enlightenment and the patriarchal robe with the words: "I make you the Sixth Patriarch."

From "Zen Buddhism: A History vol.1" by Heinrich Dumoulin, 1994