The ĀnāpāĀnāpānasati Sutta (Pāli) or Ānāpānasmṛti Sūtra (Sanskrit), "Breath-Mindfulness Discourse," Majjhima Nikaya 118, is a discourse that details the Buddha's instruction on using awareness of the breath (anapana) as an initial focus for meditation.
The sutta includes sixteen steps of practice, and groups them into four tetrads, associating them with the four satipatthanas (placings of mindfulness). According to American scholar monk, Thanissaro Bhikkhu, this sutta contains the most detailed meditation instructions in the Pali Canon.
Versions of the text
Theravada Pali Canon
The Theravada Pali Canon version of the Anapanasati Sutta lists sixteen steps to relax and compose the mind and body. The Anapanasati Sutta is a celebrated text among Theravada Buddhists. In the Theravada Pali Canon, this discourse is the 118th discourse in the Majjhima Nikaya (MN) and is thus frequently represented as "MN 118". In addition, in the Pali Text Society edition of the Pali Canon, this discourse is in the Majjhima Nikaya (M)'s third volume, starting on the 78th page and is thus sometimes referenced as "M iii 78".
Summary of the Pali Canon version
Benefits
The Buddha states that mindfulness of the breath, "developed and repeatedly practiced, is of great fruit, great benefit." It fulfills the Four Foundations of Mindfulness (satipatthana). When these are developed and cultivated, they fulfill the Seven Factors of Enlightenment (bojjhanga). And when these are developed and cultivated, they fulfill "knowledge and freedom" (Bhikkhu Sujato), "true knowledge and deliverance" (Bhikkhu Bodhi), or "clear vision and deliverance" (Nanamoli).
Establishing mindfulness
To develop and cultivate mindfulness of breathing, a monk goes to the wilderness or forest, or to the root of a tree, or to an empty hut, sits down with crossed legs and the body erect, and establishes mindfulness in front or right there (parimukham), and mindfully breathes in and out.
Four tetrads
The Ānāpānasati Sutta then describes the monitoring of the breath, and relates this to various experiences and practices. Following the classification of the four satipatthanas, these experiences and practices are grouped into a list of sixteen objects or steps of instructions, generally broken into four tetrads. These core sixteen steps are one of the most widely taught meditation instructions in the early Buddhist texts. They appear in various Pali suttas like the Ananada sutta, not just the Anapanasati sutta. They also appear in various Chinese translations of the Agamas (such as in a parallel version of the Ananada sutta in the Samyukta-Agama, SA 8.10) with minor differences as well as in the Vinayas of different schools. They are as follows: