Tirmidhi

Explanation:
1:
In this hadith, there is a prohibition against eating excessively and an encouragement towards eating less. There is no doubt, and the consensus of scholars and physicians is upon this, that eating less is beneficial for health.

Benefits and Issues:
(1)
Food consumed in excess of necessity is not digested and is expelled from the body without providing any benefit; therefore, one should eat only as much as can be fully digested and prove beneficial for the body.

(2)
The purpose of eating is to sustain life; therefore, instead of spending time preparing and consuming various elaborate dishes, time should be spent in some virtuous, beneficial, and purposeful activity.

Takhrij:
«صحيح»
[ترمذي 2380],
[حاكم 4/121],
[احمد 4/132],
[ابن حبان 1349],
In Musnad Ahmad, its chain is as follows:
«حدثنا ابوالمغيره قال حدثنا سليمان بن سليم الكناني قال حدثنا يحيي بن جابر الطائي قال سمعت المقدام بن معديكرب قال سمعت رسول الله صلى الله عليه وسلم»
"Shaykh al-Albani has declared this chain to be authentic and connected, and the hadith to be authentic. For details, see Irwa’ al-Ghalil [7/41-42]. Al-Tirmidhi said: It is hasan sahih. Al-Hakim remained silent about it, and al-Dhahabi said «قلت : صحيح»."
The remaining part of this hadith is:
«بحسب ابن آدم اكلات يعمن صلبه فان كان لا محالة فثلث لطعامه وثلث لشرابه وثلث للنفس»
"The son of Adam needs only a few morsels to keep his back straight. But if he must eat, then a third for food, a third for drink, and a third for breath."
In Sahih Ibn Hibban it is:
«فان كان فاعلا لا محالة . . . الخ»
And in Ibn Majah:
«فان غلبت الآدمي نفسه فثلث للطعام وثلث للشراب وثلث للنفس» [صحيح ابن ماجه 2704]
"So if a man is overcome by his self, then let him make a third for food, a third for drink, and a third for breath."

Benefits:
➊ This hadith condemns eating to fullness, because it is harmful both to a person’s body and to his religion. Eating more than needed causes various diseases, makes a person’s temperament heavy, and thus he cannot easily fulfill Allah’s commands.
➋ Ibn Rajab said: When Ibn Abi Maswiyah, the physician, read this hadith, he said: If people acted upon it, they would be safe from diseases, and hospitals and pharmacies would become useless. [توضيح]
The famous Arab physician Harith ibn Kaladah said: "The stomach is the house of disease, and abstinence is the basis of treatment."
➌ Eating excessively leads to the need to drink more water, which results in more sleep, and more frequent need for urination and defecation. Most of a person’s precious life is wasted in these things.
➍ Excessive eating increases greed. To fulfill it, a person spends more and more time acquiring food and drink. First, he must have enough income to satisfy his desires, then buying things, then preparing more and more delicious foods—ultimately, he departs from this world while filling this evil vessel.
➎ Excessive eating causes useless substances to accumulate in the stomach, foul vapors rise to the brain, and poisonous substances and fermentation develop in the stomach and intestines, causing various diseases. Diabetes, blood pressure, ulcers, blockage in the heart’s arteries, etc., are all results of overeating. Gradually, the stomach begins to swell and the body becomes fat, which itself is a disease and a calamity. The spiritual harm is that the temperament becomes sluggish, the light of the heart is extinguished, resolve becomes weak, and despite being fat, one becomes weak.
➏ As a result of eating more and more nourishing and delicious foods, lust increases. Due to greed, the temperament is already undisciplined. Thus, one is always at risk of falling into sin.
➐ The cure for all these diseases is to eat less, which reduces greed. The temperament becomes alert, the mind awake, the heart illuminated, the body light and strong. Most diseases do not come near. Much time becomes available for obedience to Allah. One can easily perform tahajjud and other acts. The inclination toward sins decreases. The commanding self (nafs al-ammarah) remains disappointed.
➑ The Messenger of Allah (sallallahu alayhi wa sallam) declared a few morsels sufficient for a person, and those too small, because in one narration the word «لقيمات» is also mentioned. [صحيح ابن ماجه 2705]
«اكلاتٌ» or «لقيماتُ» is a sound feminine plural which is indefinite and without the definite article, and is generally used for a small number, which applies from three to ten. If one can be patient, this is the best amount sufficient for a person. If the self prevails, then the final limit is that after filling one part with food and one with drink, the third part should be left empty for breath. If one eats more than this, it is extravagance.
➒ Some Sufis, in extolling the virtue of hunger, went so far as to abandon Allah’s blessings altogether. Some stopped drinking milk, others stopped eating delicious foods. This method is also contrary to the example of the Messenger (sallallahu alayhi wa sallam). «وَكُلُوا وَاشْرَبُوا وَلَا تُسْرِفُوا» [7-الأعراف:31] "Eat and drink, but do not be extravagant." It is also extravagance to keep one’s self in the torment of hunger. The Messenger of Allah (sallallahu alayhi wa sallam) said: «ان لنفسك عليك حقا» [صحيح بخاري]
"Indeed, your self has a right over you." And it is extravagance to keep filling this evil vessel.

Takhrij:
«أخرجه الترمذي، الزهد، باب ما جاء في كراهية كثرة الأكل، حديث:2380.»©Explanation:
➊ In this hadith, overeating (excessive eating) is declared to be the worst trait.
➋ Overeating is the root of many religious and worldly harms and corruptions. Such a person remains preoccupied only with food and drink, and often he does not even distinguish whether the food with which he is filling his stomach is lawful (halal) or not.
➌ Overeating is also a cause of stomach diseases, and it has negative effects on the heart and mind as well.
➍ In Sunan Ibn Majah, it is narrated that the Messenger of Allah (sallallahu alayhi wa sallam) said: "Those who indulge in overeating in this world will remain hungry for a longer period on the Day of Resurrection." (Sunan Ibn Majah, Al-At'imah, Chapter: Moderation in Eating and Dislike of Fullness, Hadith: 3350, 3351) Therefore, this habit is a cause of harm in both this world and the Hereafter.
Imam Ghazali rahimahullah, in Ihya' al-Ulum, has mentioned ten harms of overeating and ten benefits of eating in moderation, which are worth considering.