坐禪三昧經 1.59

1.59

已得數法，當行隨法，斷諸思覺，入息至竟，當隨莫數一；出息至竟，當隨莫數二。譬如負債人，債主隨逐，初不捨離。如是思惟是入息，是還出更有異？出息是還入，更有異？是時知入息異、出息異。何以故？出息暖、入息冷。

"Having mastered the method of counting, one should practice the method of following to sever all discursive thoughts: when an inhalation reaches its end, one should follow it and not count one; when an exhalation reaches its end, one should follow it and not count two. It is like a creditor who follows behind a debtor, never departing from him. One reflects in this way: Does this inhalation go back out, or is there another different one? Does this exhalation go back in, or is there another different one? At this time, one knows that the inhalation is different and the exhalation is different. Why is this? The exhalation is warm, and the inhalation is cool."