Praying in a home that was built using an interest-based loan
Question

                I have a brother who built his home using an interest-based loan. When I visit my brother I eat in his home and pray. What is the ruling on this? Will my prayer be valid in that home, and is it permissible to eat there or not?.
Praise be to Allah.
    Taking out riba-based loans is emphatically haraam, because 
    of the warnings and curses that have been narrated concerning that, whether 
    it is for building a house, buying a car or anything else. 

    The one who has fallen into this sin must repent to Allaah 
    and resolve never to do anything like that again. 

    But he may use and benefit from what he bought or built with 
    this loan, such as a house etc, because the money that was borrowed on the 
    basis of riba belongs to him, and what he does with it of buying or building 
    is valid. 

    Based on that, there is nothing wrong with you entering his 
    house and praying there, or eating his food, so long as you call on him to 
    repent and regret what he did before. 

    See also the answer to question no.
    22905 

    And Allaah knows best.