六祖大師法寶壇經 1.109

1.109

Zhichang asked the Master one day, "The Buddha taught the triyāna Dharma, and also spoke of the Supreme Vehicle. Your disciple does not understand; I wish you would instruct me."
The Master said, "Observe your own fundamental mind, and do not cling to external phenomenal characteristics. The Dharma does not have four vehicles; the human mind itself has gradations. Seeing, hearing, and reciting is the Small Vehicle; awakening to the Dharma and understanding the meaning is the Middle Vehicle; cultivating according to the Dharma is the Mahāyāna; thoroughly penetrating all phenomena, being fully equipped with all phenomena, being unsoiled by anything, being free from all phenomenal characteristics, and attaining nothing whatsoever is called the Supreme Vehicle. 'Vehicle' means practice; it is not a matter for verbal dispute. You must cultivate it yourself; do not ask me. At all times, the svabhāva is spontaneously as it is."
Zhichang bowed in gratitude, attended upon him, and served him until the end of the Master's life.