What is the ruling on accepting aid and prizes offered by a usurious bank?

It is not permissible to deal with usurious banks, whether by borrowing or lending, nor to do anything that assists them in their operations, due to the Almighty's saying: "And do not cooperate in sin and aggression." Usurious banks conduct permissible transactions such as transfers and currency exchange, and their funds consist of shareholders' capital, transfer fees, exchange profits, and usurious interest. If it is known that the money given to the poor is purely usurious interest, then it is not permissible for them to take it, and the bank must return it to its owners. However, if it is not known to be usury and no one else has a claim to it, then it is permissible to take it with the intention that it comes from the bank's legitimate sources of funds, although avoiding this is preferable. It is not permissible to take it if doing so aids the bank in continuing its operations or encourages people to deal with it.