It is narrated from Sayyiduna al-Miqdam bin Ma'dikarib al-Kindi (may Allah be pleased with him) that he said: I heard the Messenger of Allah (peace and blessings be upon him) saying: "The son of Adam has not filled any vessel worse than his stomach. Three morsels are enough for the son of Adam to keep his back upright. But if (eating more) is unavoidable, then let him keep one third for his food, one third for his drink, and one third (empty) for his breath." This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.