Is the money a father spends on his son permissible, even though the father works in farming and trade and deposits his money in a usurious bank without taking the usurious interest due to the absence of Islamic banks in the country, and is the money considered unlawful if the son is scrupulous and fears the impermissibility of this money?

There is no harm in benefiting from the father's money acquired through a legitimate profession, even if he deposits it in interest-bearing banks for safekeeping, provided that he is advised to open a current account and withdraw the usurious interest to give it to the poor and needy or for general Muslim welfare. Al-Nawawi mentioned that if illicit money reaches a poor person, it becomes lawful and pure for them, and they may spend it on themselves and their families if they are poor.