Is it permissible to take out an interest-bearing loan to pay off debts for household furniture and debts to relatives, or is it obligatory to sell the house to pay off these debts?

It is forbidden to borrow with usury unless there is a necessity defined as an imminent danger to one's life, honor, intellect, or property that cannot be averted except by committing what is forbidden, such as imprisonment. If the matter does not reach that point, it is not considered a necessity. The son is not obligated to pay usurious installments unless he has purchased something. However, out of filial piety, and to protect him and his family from usury and litigation, if it is possible to sell the house and move to a less expensive one to pay off the debt, then he should do so.