坐禪三昧經 1.66

1.66

念息出入，譬如守門人門邊住，觀人入出。止心亦爾！知息出時，從臍、心、胸、咽至口、鼻。息入時從口、鼻、咽、胸、心至臍。如是繫心一處，是名為止。

"Being mindful of the breath exiting and entering is like a gatekeeper standing by the gate, observing people entering and exiting. Stopping the mind is also like this! When the breath exits, one knows it passes from the navel, heart, chest, and throat to the mouth and nose. When the breath enters, it passes from the mouth, nose, throat, chest, and heart to the navel. Tying the mind to a single place in this way is called 'stopping.'"