Is borrowing from the bank with interest to buy an apartment for housing forbidden (haram), and is it necessary to repay the loan in full before going for Hajj?

It is not permissible to take a loan with interest from a bank to purchase an apartment or anything else, because it is usury (riba), which is forbidden by Islamic law. Whoever has done so must repent to Allah. If it is possible for him to extricate himself from the transaction by returning the principal and having the bank waive the interest, he should do so, based on the words of Allah Almighty: "And if you repent, you will have your principal sums. You do not wrong, and you are not wronged." If he is unable to do so, then he should pay what was agreed upon and not return to such a practice. It is not obligatory to pay the full amount before Hajj unless it affects the principal installments. As for the interest installments, the obligation is to refrain from paying them unless there is considerable coercion. Repentance from sins before Hajj is obligatory.