"There is the case where a monk, having gone to the wilderness, to the shade of a tree, or to an empty building, sits down folding his legs crosswise, holding his body erect, and setting mindfulness to the fore. Always mindful, he breathes in; mindful he breathes out.
"Breathing in long, he discerns that he is breathing in long; or breathing out long, he discerns that he is breathing out long. Or breathing in short, he discerns that he is breathing in short; or breathing out short, he discerns that he is breathing out short. He trains himself to breathe in sensitive to the entire body, and to breathe out sensitive to the entire body. He trains himself to breathe in calming the bodily processes, and to breathe out calming the bodily processes.
"He trains himself to breathe in sensitive to rapture, and to breathe out sensitive to rapture. He trains himself to breathe in sensitive to pleasure, and to breathe out sensitive to pleasure. He trains himself to breathe in sensitive to mental processes, and to breathe out sensitive to mental processes. He trains himself to breathe in calming mental processes, and to breathe out calming mental processes.
"He trains himself to breathe in sensitive to the mind, and to breathe out sensitive to the mind. He trains himself to breathe in satisfying the mind, and to breathe out satisfying the mind. He trains himself to breathe in steadying the mind, and to breathe out steadying the mind. He trains himself to breathe in releasing the mind, and to breathe out releasing the mind.
"He trains himself to breathe in focusing on inconstancy, and to breathe out focusing on inconstancy. He trains himself to breathe in focusing on dispassion, and to breathe out focusing on dispassion. He trains himself to breathe in focusing on cessation, and to breathe out focusing on cessation. He trains himself to breathe in focusing on relinquishment, and to breathe out focusing on relinquishment."
(adapted from The Samyutta Nikaya 54.13,)