Is it permissible to obtain an interest-bearing loan to pay off a brother's right, and would I be sinful if I helped my parents obtain the loan with the intention of providing housing for them?

It is not permissible for a son to mistreat his parents verbally or physically, nor to force them to sell their home to pay off a debt they owe. Rather, he must spend on them if he is able. It is not permissible for the father to borrow with interest to give money to the son, and it is not permissible for the brother to guarantee this forbidden loan. The brother's threat to harm himself should not be heeded, as his sin is upon him alone. If he persists in his transgression, his father may report him to the police to protect them from him.