He sweats and it smells, but it is too difficult for him to do ghusl for every prayer
Question

                There is a person who sweats a great deal and he needs to take a bath for every prayer (so that he will not annoy other worshippers). Is this an excuse for not offering some of the obligatory prayers in the mosque or not? Especially since it is sometimes difficult to take a bath all the time, such as when it is cold at the time of Fajr prayer?.
Praise be to Allah.
    If a person has the problem of offensive body odour, and he 
    cannot conceal it by using perfume and the like, then he is excused for not 
    praying in congregation and there is the hope that he will be rewarded by 
    Allah. If bathing will remove this smell, then he should do it as much as he 
    can. Allah has made the means that help with that readily available, such as 
    hot water and the ability to protect oneself against cold by wearing warm 
    clothes, and the like. 

    The fuqaha’ have stated that the presence of an offensive 
    smell is an excuse for not praying in congregation. In fact they tell the 
    one who has a smell not to enter the mosque and annoy the worshippers. 

    The basic principle with regard to that is the report 
    narrated by Muslim (564) from Jaabir ibn ‘Abd-Allaah (may Allah be pleased 
    with him) from the Prophet (blessings and peace of Allah be upon him) who 
    said: “whoever eats garlic, onions or leeks, let him not come near our 
    mosque, for the angels are offended by the same things that offend the sons 
    of Adam.” 

    It says in Mataalib Ooli al-Nuha (1/699): It is 
    makrooh to attend the mosque and prayer in congregation for the one who eats 
    garlic, onions, or leeks, and anything that has an offensive smell, until 
    that smell has gone. The same applies to one who has bad breath or body 
    odour from the armpits or anything that has a rotten smell. It is mustahabb 
    to make them leave, so as to ward off annoyance. 

    It says in Asna al-Mataalib (1/215): From what is 
    mentioned, it may be understood that if the person who has a chronic and 
    serious problem with bad breath and body odour, it is more appropriate for 
    him to be excused from coming to the mosque to pray in congregation. End 
    quote. 

    Shaykh Ibn Baaz (may Allah have mercy on him) was asked: My 
    father is elderly and does not go to pray in congregation, and he says that 
    he is ill with something that causes bad breath and an unpleasant smell, and 
    he says that he does not want to annoy the people with this smell. Is it 
    permissible for him to do this?  

    He replied: Yes, this is a legitimate excuse. If he has 
    severe halitosis that smells bad and he cannot remove it, then he is 
    excused. Similarly, onions or leeks are an excuse. But if there is any 
    remedy or a way to remove the smell, then he must do that, so that he will 
    not stay away from Jumu’ah prayer and prayers in congregation. But if he is 
    unable to do that and it is not easy for him, then his excuse is stronger 
    than the excuse of the one who eats onions. Undoubtedly bad breath is 
    annoying to the people around him, if the smell is obvious. End quote from
    Noor ‘ala al-Darb (tape no. 219, minute 11). 

    We ask Allah to heal you and give you good health. 

    And Allah knows best.