In a story told in Chan Buddhism, the Buddha once held up a flower before the assembly on Vulture Peak. Everyone was silent and did not understand. Only his disciple Mahakashyapa smiled. The Buddha then said that he would entrust his true teaching to Mahakashyapa, “not founded on words, a separate transmission outside the scriptures” (不立文字，教外别传).
The earliest known version of the story dates from 1036. The words “a separate transmission outside the scriptures, not founded on words” became a motto of Chan.