"Whoever pervades the great ocean with his awareness encompasses whatever rivulets flow down into the ocean. In the same way, whoever develops & pursues mindfulness immersed in the body encompasses whatever skillful qualities are on the side of clear knowing."
"When one thing is practiced & pursued, the body is calmed, the mind is calmed, thinking & evaluating are stilled, and all qualities on the side of clear knowing go to the culmination of their development. Which one thing? Mindfulness immersed in the body."
"When one thing is practiced & pursued, ignorance is abandoned, clear knowing arises, the conceit 'I am' is abandoned, latent tendencies are uprooted, fetters are abandoned. Which one thing? Mindfulness immersed in the body."
"Those who do not taste mindfulness of the body do not taste the Deathless. Those who taste mindfulness of the body taste the Deathless."
"Those who are heedless of mindfulness of the body are heedless of the Deathless."
"Those who comprehend mindfulness of the body comprehend the Deathless."
— AN 1.225, 227, 230, 235, 239, 245
http://www.accesstoinsight.org/lib/study/bodymind.html#part2