How can one purify their money from usury when they cannot withdraw any amount from their inheritance deposited in a usurious bank except with the permission of their mother who deposited it in this bank?

It is not permissible to deal with usurious banks or to deposit money in them, because they are openly engaged in sin, and dealing with them is cooperation in sin and aggression. The money must be withdrawn from them if possible, and the responsible individual must protect their religion and their money. The mother should be advised gently and kindly to withdraw her money, and the prohibition of usury and its punishment should be explained to her. The mother must fear Allah and stay away from unlawful money, for "a single dirham of usury that a man consumes knowingly is worse than thirty-six acts of adultery."