Is it permissible to open an account in a usurious bank for international commercial dealings due to the unavailability of Islamic banks, and what is the ruling on money deposited in a conventional bank without taking or donating the interest?

It is not permissible to open accounts in usurious banks, because it involves aiding in sin, unless a Muslim is compelled to do so, such as the absence of a safe place for his money, or his need to complete his work. In such cases, it is permitted for him, provided that the account is interest-free.

If a person cannot conduct external transactions except through usurious banks and finds no alternative, there is no harm in dealing with them regarding current accounts. If he receives interest without having contracted for it, he must spend it on general Muslim welfare, such as mosques and roads, or give it to the poor.