南宗頓教最上大乘摩訶般若波羅蜜經六祖惠能大師於韶州大梵寺施法壇經 1.52

1.52

At that time there was a monk named Zhichang, who came to Caoxi Mountain, bowed in homage to the Reverend, and asked about the meaning of the teachings of the four vehicles. Zhichang asked the Reverend, saying, "The Buddha spoke of three vehicles, and also spoke of the Supreme Vehicle. Your disciple does not understand and hopes for your instruction." Master Huineng said, "Look into your own body and mind, do not become attached to external phenomenal characteristics; originally there is no teaching of four vehicles. It is because human minds have four grades of capacity that there are four vehicles in the Dharma. Seeing, hearing, and reciting is the Small Vehicle; awakening to the Dharma and understanding the meaning is the Middle Vehicle; practicing according to the Dharma is the Great Vehicle. To fully penetrate the ten thousand dharmas, to be complete in all ten thousand practices, not abandoning anything yet abandoning phenomenal characteristics, acting without any attainment—this is the Supreme Vehicle. The Supreme Vehicle is the meaning of the highest practice, not to be disputed with the mouth. You must cultivate it yourself; do not ask me."