A son argues with his parents about food and prayer
Question

 
My brother is very fat and he eats a lot. Every time my mother advises him to eat less, and warns that she will not be pleased with him if he does not listen to her, he says that eating is not haraam and a mother has no right to stop him doing something that is permissible. 
Also, he does not pray in the mosque. Every time my mother asks him, “Why don’t you go?” he says, “Prayer in congregation is a confirmed Sunnah, as Imam Abu Haneefah says.” 
He also delays prayer for a long time after the adhaan, and every time we ask him, “Why don’t you pray on time?” he says, “I do not go beyond the specified time, and the prayers have times that are not limited by the adhaan and iqaamah.” How should we respond to him?.
Praise be to Allah.Firstly: 
One of the greatest blessings that Allah has bestowed upon His slaves is that He has subjugated to them everything that is on earth, and He sends down blessings upon them, and He has permitted to them all good kinds of food, drink, clothing and so on. 
But Allah also condemns everyone who is extravagant in his use of these permissible things, or who abuses these blessings in ways that harm him or distract him from that which will benefit his religious and worldly interests. 
Allah says (interpretation of the meaning): 
“and eat and drink but waste not by extravagance, certainly He (Allah) likes not Al‑Musrifoon (those who waste by extravagance)”
[al-A’raaf 7:31]
Secondly: 
One of the most dangerous things that may doom the son of Adam to Hell is the desire of his belly, as the belly is the basis of all other desires and the essence of all problems and diseases. The Prophet (peace and blessings of Allah be upon him) said: “The son of Adam does not fill any vessel worse than his stomach. It is sufficient for the son of Adam to eat a few morsels to keep him alive. If he must fill it, then one-third for his food, one-third for his drink, and one-third for air.” Narrated by al-Tirmidhi (2380), classed as saheeh by al-Albaani in Saheeh al-Tirmidhi. 
i.e., it is sufficient for the son of Adam to eat only that which will keep him alive, and no more than that. If he insists on having more, then he should eat only that which will fill one-third of his stomach, and another third for drink, and leave one-third for air. He should not consume more than that amount. 
See: Tuhfat al-Ahwadhi. 
The wise men of the Jaahiliyyah and of Islam were praised for eating little. 
Haatim al-Taa’iy said: 
If you give your stomach and your private part what they ask for, you will end up regretting it. 
Fath al-Baari (9/669) 
If a person eats so much food that it harms him, this is haraam. 
The scholars of the Standing Committee were asked: Is eating too much haraam? 
They replied: 
Yes, it is haraam for a Muslim to eat so much that it harms him, because that is a kind of extravagance and extravagance is haraam, because Allah says (interpretation of the meaning): 
“and eat and drink but waste not by extravagance, certainly He (Allah) likes not Al‑Musrifoon (those who waste by extravagance)”
[al-A’raaf 7:31]. End quote. 
Fataawa al-Lajnah al-Daa’imah (22/329). 
Warnings have been narrated from the Prophet (peace and blessings of Allah be upon him) about eating one’s fill too often, and that this is a cause of suffering from hunger on the Day of Resurrection. It was narrated that Ibn ‘Umar (may Allah be pleased with him) said: A man burped in the presence of the Messenger of Allah (peace and blessings of Allah be upon him) and he said: “Keep your burps away from us, for the one who eats his fill the most in this world will be hungry for the longest time on the Day of Resurrection.” Narrated by al-Tirmidhi (2015); classed as saheeh by al-Albaani in Saheeh al-Tirmidhi. 
It was also narrated by Ibn Abi’l-Dunya,  al-Tabaraani in al-Kabeer and al-Awsat and by al-Bayhaqi, from Abu Juhayfah, and they added: Abu Juhayfah did not eat his fill until he departed this world; if he ate breakfast he would not eat dinner and if he ate dinner he would not eat breakfast. According to a report narrated by Ibn Abi’l-Dunya: Abu Juhayfah said: I have not filled my stomach for thirty years.  
See: Tuhfat al-Ahwadhi. 
The way to stop eating too much is to stop gradually. If a person is used to eating a lot and he goes in one fell swoop to eating little, he will become weak and his appetite will increase. So he should reduce it gradually, by eating less and less of his usual food, until he reaches a moderate intake of food. 
Thirdly: 
If prayer in congregation is Sunnah mu’akkadah (a confirmed Sunnah) or prayer at the beginning of its time is better, that means that we should be eager to do that, not that we may neglect it or be heedless about doing it. We should praise Allah for having prescribed the ways of guidance and the rituals of worship for us, and we should learn from the experience of our predecessors of the first generation. 
Ibn Mas’ood (may Allah be pleased with him) said: Whoever would like to meet Allah, may He be exalted, tomorrow as a Muslim, let him regularly offer these prayers where the call to prayer is given, for Allah has prescribed the Sunnahs of guidance to your Prophet (S) and they (the prayers) are among the Sunnahs of guidance. If you pray in your houses like this one who stays away from the mosque prays in his house, you will have forsaken the Sunnah of your Prophet, and if you forsake the Sunnah of your Prophet you will go astray. There is no man who purifies himself and purifies himself well, then he goes to one of these mosques, but Allah will record one good deed for him for every step he takes, and will raise him in status one degree thereby, and will erase one bad deed thereby. I remember when no one would stay away but a hypocrite whose hypocrisy was known, and a man would come staggering between two others in order to stand in the row. Narrated by Muslim (654). 
This is based on the assumption that prayer in congregation is Sunnah mu’akkadah. But we have explained that it is obligatory, and quoted the evidence for that, in the answers to many questions. See questions no. 8918, 10292, 21498 and 40113. 
We ask Allah to help us and you to do that which He loves and which pleases Him. 
And Allah knows best.