He became junub in his friend’s house and he is afraid that he may be accused of impropriety
Question

                A man invited me to his home, and I slept there that night. I woke up junub and he called me to pray Fajr together in his home. Should I have accepted praying with him in this case, or refuse? As he has a wife and I fear if I say I am junub, he doubts his wife.
Praise be to Allah.
    If you become junub, you have to do ghusl so that you will be 
    able to pray. It is not permissible for you to pray if you are junub, and 
    wudoo’ cannot take the place of ghusl, but if you cannot find water or you 
    find cold water, and you cannot find any means of heating it, and you fear 
    that you may be harmed by using it, then you can do tayammum. 

    As for not doing ghusl because you felt shy and embarrassed, 
    that is not permissible and that does not make it permissible for you to do 
    tayammum. 

    Praying when junub is a grave wrong, and you have to repent 
    from it, because the Prophet  (peace and blessings of Allaah be upon 
    him) said: “No prayer is accepted without purification, and no charity (is 
    accepted) that comes from stolen wealth .” Narrated by Muslim (224). 

    And the Prophet  (peace and blessings of Allaah be upon 
    him) told us that prayer offered without purification is one of the things 
    for which a person will be punished in the grave. This has been explained in 
    the answer to question no. 65731. 

    Your fear of Allaah should be greater than your fear of 
    people, as Allaah says (interpretation of the meaning): 

    “Therefore fear not men but fear Me”

    [al-Maa’idah 5:44] 

    “Do you fear them? Allaah has more right that you should 
    fear Him if you are believers”

    [al-Tawbah 9:13]. 

    The shyness that keeps you from doing obligatory duties is a 
    blameworthy kind of shyness, rather it is weakness and incapability. 

    If you had gone out to the mosque and done ghusl there, and 
    prayed, you would have been spared any embarrassment. 

    And Allaah knows best.