मज्झिम निकाय 3:67
SUJATO‘passambhayaṁ cittasaṅkhāraṁ assasissāmī’ti sikkhati, ‘passambhayaṁ cittasaṅkhāraṁ passasissāmī’ti sikkhati.
They practice like this: ‘I’ll breathe in stilling the mental process.’ They practice like this: ‘I’ll breathe out stilling the mental process.’