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 the body (Kaayaanusmriti).”
The Budha addressed the bhikshus:
“How does practicing mindfulness of body 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 the body, he will reflect on the body as follows:
What is this body?
It is composed of hair, nails, teeth, skin, flesh, tendons, bones, marrow, kidneys, heart, liver, spleen, lungs, large intestines, small intestines, stomach, feces, urine, bile, phlegm, pus, blood, fat, grease, sweat, tears, saliva, mucus, and brain.
Is this body made of the earth element?
The water element?
The fire element?
The wind element?
Is it created by the union of father and mother?
Where does it come from?
Who created it?
Where will the eyes, ears, nose, tongue, body, and mind go after death?
Thus, bhikshus, this is called mindfulness of the body, 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 the body. 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.