What is the ruling on dividing a sum of money that has accrued usurious interest without the depositor's knowledge, and is it permissible for the heirs to benefit from this increase?

Only the principal amount of the wealth enters into inheritance. As for the usurious excess interest, it is not permissible to distribute it as part of the inheritance. It must be disposed of by spending it on charitable causes, such as giving it to the poor and needy, even if they are relatives. Ignorance of the unlawfulness of earnings does not make them permissible. It is obligatory to seek religious knowledge and consult scholars before any statement or action.