al-Hasan bin Sa'd bin Ma'bad الحسن بن سعد بن معبد · Chapters on Food

“I heard the Messenger of Allah (ﷺ) say: ‘A human being fills no worse vessel than his stomach. It is sufficient for a human being to eat a few mouthfuls to keep his spine straight. But if he must (fill it), then one third of food, one third for drink and one third for air.’”