Is it Islamically permissible to purchase a house owned by the heirs of the grandfather — a house that the father contributed to building and that the questioner expanded — using a bank loan from the paternal uncles and aunts, knowing that one of the paternal uncles resides in the house while the rest of the heirs do not need it?

There are two scenarios for borrowing from a bank: a benevolent loan (qard hasan) without interest, which is permissible, and an interest-bearing loan, which is prohibited usury (riba) unless it is a matter of extreme necessity that cannot be averted otherwise. The need to purchase a home is not considered a necessity that permits usury.

As for purchasing a home through the bank, there are two scenarios: the bank financing in exchange for interest, which is a prohibited usurious loan. Or, the bank purchases the home and then sells it to you in installments at a higher price; this is permissible provided that the contract does not include a penalty for late installments, as that would be prohibited usury.

Allah Almighty has declared war on those who consume usury. The Prophet, peace and blessings be upon him, cursed the one who consumes usury, the one who feeds it to others, its scribe, and its two witnesses. He also considered one dirham of usury to be worse than thirty-six acts of fornication.