Thus have I heard:
One time, the Budha was staying at Anaathapindidas Ashrama in Jetavana of Shraavastii.
At that time, the Bhagavaan addressed the bhikshus:
“Practice one dharma,
And widely propagate one dharma.
Having practiced this one dharma,
You will gain renown,
Attain great merits,
Experience all wholesome qualities,
Taste the nectar of liberation,
Reach the unconditioned state,
Attain spiritual powers,
Dispel distracting thoughts,
Achieve the fruits of the Shramana path,
And realize Nirvaana.
What is this one dharma?
It is mindfulness of breathing (Aana-apaana-anusmriti).”
The Budha addressed the bhikshus:
“How does practicing mindfulness of breathing lead to renown, great fruits, the arising of all wholesome qualities, the taste of the nectar of liberation, the attainment of the unconditioned state, the realization of spiritual powers, the dispelling of distracting thoughts, the achievement of the Shramana fruits, and the realization of Nirvaana?”
At that time, the bhikshus addressed the Bhagavaan:
“The source of all dharmas is spoken by the Tathaagata. We beseech the Bhagavaan to explain this profound meaning to the bhikshus. Having heard it from the Tathaagata, we will uphold and practice it.”
At that time, the Bhagavaan addressed the bhikshus:
“Listen carefully! Listen carefully! Reflect deeply on this, for I will explain it to you in detail.”
The bhikshus replied: “So it is, Bhagavaan.”
The bhikshus then respectfully accepted the teaching.
The Bhagavaan said:
“If a bhikshu, with upright body and mind, sits cross-legged, fixes his mindfulness, and is free from distracting thoughts, single-mindedly practicing mindfulness of breathing, he will reflect on the breath as follows:
When the breath is long, he will know, ‘My breath is long.’
When the breath is short, he will know, ‘My breath is short.’
When the breath is cool, he will know, ‘My breath is cool.’
When the breath is warm, he will know, ‘My breath is warm.’
He will observe the entire body,
From the head to the feet,
And be fully aware of it.
If the breath is long or short,
He will observe and know it.
With a focused mind, he will discern the length and rhythm of the breath,
Clearly understanding the in-breath and out-breath.
Thus, bhikshus, this is called mindfulness of breathing, which leads to great fruits, the arising of all wholesome qualities, the taste of the nectar of liberation, the attainment of the unconditioned state, the realization of spiritual powers, the dispelling of distracting thoughts, the achievement of the Shramana fruits, and the realization of Nirvaana.
Therefore, bhikshus, always reflect and never stray from mindfulness of breathing. In this way, you will attain these virtuous qualities.
Thus, bhikshus, you should train yourselves in this manner.”
When the bhikshus heard what the Budha said, they followed it with joy.