Anapanasati Sutta
The Ānāpānasati Sutta (Pāli) or Ānāpānasmṛti Sūtra (Sanskrit), "Breath-Mindfulness Discourse," is a discourse that details the Buddha's instruction on using the breath (anapana) as a focus for meditation.
Read more about Anapanasati Sutta: Related Canonical Discourses, Pali Commentaries, Interpretations