摩訶止觀 2.6

2.6

身開常坐，遮行住臥。或可處眾，獨則彌善。居一靜室，或空閑地，離諸喧鬧，安一繩床，傍無餘座。九十日為一期，結跏正坐，項脊端直，不動、不搖、不萎、不倚，以坐自誓。肋不拄床，況復屍臥、遊戲、住立？除經行、食、便利，隨一佛方面，端坐正向，時刻相續，無須臾廢。所開者，專坐；所遮者，勿犯。不欺佛，不負心，不誑眾生。

For the body, permission is given for constantly sitting, while walking, standing, and lying down are prohibited. One may be among an assembly, but being alone is even better. Reside in a quiet room or an empty, quiet place, free from noisy bustle, setting up a single corded bed with no other seat beside it. Take ninety days as one period. Sit upright in the lotus posture, with neck and spine erect and straight, without moving, shaking, drooping, or leaning, taking sitting as one's vow. The ribs must not touch the bed, much less lying like a corpse, sporting, or idling standing. Except for walking meditation, eating, and urinating or defecating, face the direction of a single Buddha, sitting upright and directly facing it, continuously from moment to moment without a moment's lapse. As for what is permitted, sit exclusively; as for what is prohibited, do not violate it. Do not deceive the Buddhas, do not betray your own mind, and do not deceive sentient beings.