I heard the Messenger of Allah ﷺ say, "The son of Adam fills no vessel worse than his stomach. A few morsels are enough for the son of Adam to keep his back straight. But if he must eat more, then let it be one third for food, one third for drink, and one third for his breath."
حدثنا أبو المغيرة قال حدثنا سليمان بن سليم الكناني قال حدثنا يحيى بن جابر الطائي قال سمعت
سمعت رسول الله ﷺ يقول ما ملأ ابن آدم وعاء شرا من بطن حسب ابن آدم أكلات يقمن صلبه فإن كان لا محالة فثلث طعام وثلث شراب وثلث لنفسه
Its isnad is sahih. Sulayman bin Sulaym Kanani Kalbi, the judge of Hims, is trustworthy, and he was praised for his asceticism and knowledge. Yahya bin Jabir bin Hassan Tai, Abu Amr Hims, also a judge, is trustworthy, and he was praised extensively. The hadith was narrated by Tirmidhi 4/590, no. 2380, in the chapter on Zuhd, on the dislike of eating too much, where he said, hasan sahih. It was also narrated by Ibn Majah 2/1111, no. 3349, and Ibn Hibban 328, no. 1348. Hakim graded it sahih, and Dhahabi agreed with him.