The Buddha explains the importance of mindfulness of the body in partaking in the deathless.
Amata vagga - The Chapter On The Deathless
1.616
"Bhikkhus, those who do not partake in mindfulness of the body do not partake in the deathless. Bhikkhus, those who partake in mindfulness of the body partake in the deathless."
1.617
"Bhikkhus, the deathless has not been partaken of by those who have not partaken in mindfulness of the body. Bhikkhus, the deathless has been partaken of by those who have partaken in mindfulness of the body."
1.618
"Bhikkhus, they have fallen away from the deathless who have fallen away from mindfulness of the body. They have not fallen away from the deathless who have not fallen away from mindfulness of the body."
1.619
"Bhikkhus, they have missed the deathless who have missed mindfulness of the body. They have not missed the deathless who have not missed mindfulness of the body."
1.620
"Bhikkhus, they were negligent of the deathless, who were negligent of mindfulness of the body. Bhikkhus, they were not negligent of the deathless, who were not negligent of mindfulness of the body."
1.621
"Bhikkhus, they have forgotten the deathless who have forgotten mindfulness of the body. They have not forgotten the deathless who have not forgotten mindfulness of the body."
1.622
"Bhikkhus, they have not pursued the deathless who have not pursued mindfulness of the body. They have pursued the deathless who have pursued mindfulness of the body."
1.623
"Bhikkhus, they have not developed the deathless who have not developed mindfulness of the body. They have developed the deathless who have developed mindfulness of the body."
1.624
"Bhikkhus, they have not frequently practiced the deathless who have not frequently practiced mindfulness of the body. They have frequently practiced the deathless who have frequently practiced mindfulness of the body."
1.625
"Bhikkhus, they have not experienced the deathless who have not experienced mindfulness of the body. They have experienced the deathless who have experienced mindfulness of the body."
1.626
"Bhikkhus, they have not completely comprehended the deathless who have not completely comprehended mindfulness of the body. They have completely comprehended the deathless who have completely comprehended mindfulness of the body."
1.627
"Bhikkhus, they have not personally realized the deathless who have not personally realized mindfulness of the body. They have personally realized the deathless who have personally realized mindfulness of the body."
The Blessed One said this. Those bhikkhus were satisfied and rejoiced in the Blessed One's words.