The hadith curses those who take interest, pay interest, record it, check it and bear witness to it. Hence the income of such person is not lawful to be used by guest too. One should avoid the partnership of such person in purchasing a house. If that manager has any other lawful source of income other than bank and that income is more than the income of bank, then it is allowed to share with him.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband