Маджхима Никая 3:62
SUJATO‘sabbakāyapaṭisaṁvedī assasissāmī’ti sikkhati, ‘sabbakāyapaṭisaṁvedī passasissāmī’ti sikkhati;
They practice like this: ‘I’ll breathe in experiencing the whole body.’ They practice like this: ‘I’ll breathe out experiencing the whole body.’