The Instructor 2.1.13

If anyone is hungry, let him eat at home, so that you may not come together for judgment.” We must abstain, then, from all servility and incontinence, touching what is set before us decorously, keeping hand and couch and chin unsoiled, preserving the good form of the face undistorted, not behaving indecently in swallowing either; but we should stretch out the hand in order and at intervals. … We must also guard against saying anything while eating; for the voice becomes unseemly and indistinct when confined by full cheeks, and the tongue, pressed by food and hindered in its natural action, gives out a crushed utterance. Nor is it fitting to eat and drink at the same time; for it is the height of incontinence to confuse the times of things whose uses do not agree. And “whether you eat,” he says, “or drink, do all to the glory of God,” aiming at true frugality, which the Lord too seems to me to have hinted at when he blessed the loaves and the broiled fish with which he feasted the disciples, introducing a fine example of simple food.