[1382] "And how, Ānanda, is concentration through mindfulness of breathing (ānāpānasati) developed, how is it cultivated, so that it fulfills the four establishments of mindfulness (satipaṭṭhāna)? Here, Ānanda, a bhikkhu, gone to the forest, or gone to the root of a tree, or gone to an empty dwelling, sits down; having folded his legs crosswise, set his body erect, and established mindfulness in front of him, just mindful he breathes in, mindful he breathes out. Breathing in long, he knows clearly, 'I breathe in long'; or breathing out long, he knows clearly, 'I breathe out long' (to be expanded in full) … He trains thus: 'Contemplating relinquishment, I shall breathe in'; he trains thus: 'Contemplating relinquishment, I shall breathe out.'
"On whatever occasion, Ānanda, a bhikkhu, breathing in long, knows clearly, 'I breathe in long'; or breathing out long, knows clearly, 'I breathe out long'; or short … he trains thus: 'Calming the bodily formation, I shall breathe in'; he trains thus: 'Calming the bodily formation, I shall breathe out' — on that occasion, Ānanda, the bhikkhu dwells contemplating the body in the body, ardent, clearly comprehending, mindful, having removed covetousness and grief regarding the world. For what reason? I say, Ānanda, that this is a certain body among bodies, namely, in-breathing and out-breathing. Therefore, Ānanda, on that occasion the bhikkhu dwells contemplating the body in the body, ardent, clearly comprehending, mindful, having removed covetousness and grief regarding the world."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.