The Related Suttas Collection 54.20

Chapter Two

The Ending of Defilements

“Bhikkhus, when samādhi due to mindfulness of breathing is developed and cultivated it leads to the ending of defilements. And how is samādhi due to mindfulness of breathing developed and cultivated so as to lead to giving up the fetters, uprooting the underlying tendencies, completely understanding the course of time, and ending the defilements?

It’s when a bhikkhu—gone to a wilderness, or to the root of a tree, or to an empty hut—sits down cross-legged, sets their body straight, and establishes mindfulness around the opening (of the nostrils). …

They practice like this: ‘I’ll breathe in watching, again and again, letting go.’ They practice like this: ‘I’ll breathe out watching, again and again, letting go.’

That’s how samādhi due to mindfulness of breathing is developed and cultivated so as to lead to giving up the fetters, uprooting the underlying tendencies, completely understanding the course of time, and ending the defilements.”

The Related Suttas Collection on Mindfulness of Breathing is the tenth section.