All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
It is prohibited for a Muslim to borrow from whom he takes usury because usury is amongst the grave sins on which Allah Has Declared war, as reflected in the following verse: " O ye who believe! Fear God, and give up what remains of your demand for usury, if ye are indeed believers. If ye do it not, Take notice of war from God and His Apostle: But if ye turn back, ye shall have your capital sums: Deal not unjustly, and ye shall not be dealt with unjustly." {Al-Baqara, 278-279}. Moreover, Narrated Jabir (RA): Allah's Messenger (PBUH) cursed the one who accepts usury, the one who gives it, the one who records it and the two witnesses to it, saying: "They are all the same." [Reported by Muslim].
It isn`t permissible for a Muslim to take usury from a bank nor give it to the latter as interest. Moreover, purchasing a flat isn`t amongst the necessities which make the unlawful lawful because the need for housing can be met by renting a house for there are millions of people who are live in rented houses. In addition, it is better for a Muslim to live in a rented house for a hundred years than live for an hour in a house he got via a usurious loan. This is because the hardship of this worldly life is nothing compared to the punishment in the Hereafter. And Allah the Almighty Knows Best.