Is money that mistakenly reached the account of a relative of mine in America, and which the bank stipulated must reach a certain amount before it can be withdrawn, unlawful (haram)? And do her two sisters sin if they take from it or help gather the required amount, knowing its source? And is it forbidden for us to eat from their food or accept gifts from them if the money is unlawful? And should the poor members of the family refuse to take from it? And how should we act to repel their financial courtesies and avoid eating their food, given that I sometimes live with them? And do we sin merely by thinking about taking a portion of this money? And must I inform their religiously committed daughter about this matter?

The account holder is not permitted to benefit from the money that was deposited, because it is either an error, in which case it must be returned to the bank, or a gift from the bank, which is usury (riba), or usurious interest. Her sister is not allowed to assist her in benefiting from it, due to the generality of Allah Almighty's saying: "And do not cooperate in sin and aggression." Nor is her vow to give a portion of it to someone valid, because it is a vow of disobedience. What is obligatory is to advise her to leave it. If she takes the money and has no other money, then it is not permissible to eat from her wealth or accept her gift. However, merely thinking about benefiting from haram wealth does not entail sin unless she speaks or acts upon it.