Vishnupurana 3.11.89

3.11.89

bhuktvā samyag athācamya prāṅmukhodaṅmukho 'pi vā
yathāvat punar ācāmet pāṇī prakṣālya mūlataḥ //

The man who commences his meal with fluids, then partakes of solid food, and finishes with fluids again, will ever be strong and healthy. In this manner let him feed without fault, silent, and contented with his food; taking, without uttering a word, to the extent of five handfulls, for the nutriment of the vital principle. Having eaten sufficiently, the householder is then to rinse his mouth, with his face turned towards the east or the north; and having again sipped water, he is to wash his hands from the wrist downwards. With a pleased and tranquil spirit he is then to take a seat, and call to memory his tutelary deity; and then he is thus to pray: 'May fire, excited by air, convert this food into the earthly elements of this frame, and in the space afforded by the etherial atmosphere cause it to digest, and yield me satisfaction! May this food, in its assimilation, contribute to the vigour of the earth, water, fire, and air of my body, and afford unmixed gratification! May Agasti, Agni, and submarine fire effect the digestion of the food of which I have eaten; may they grant me the happiness which its conversion into nutriment engenders; and may health ever animate my form! May Vishńu, who is the chief principle of all invested with bodily structure and the organs of sense, be propitiated by my faith in him, and influence the assimilation of the invigorating food which I have eaten!