Is a father's will to deposit a sum of money in the bank to benefit from its profits during his lifetime, or to distribute it for charitable purposes after his death as an ongoing charity (ṣadaqah jāriyah), obligatory to implement? Or should the principal amount be returned to the legal heirs?

Your father bequeathed this money as an endowment after his death, so that its profits may be spent on charitable causes. This is a permissible bequest that the heirs must execute, provided it does not exceed one-third of the estate. Anything exceeding one-third is not executed unless the heirs consent. You must execute the bequest within this limit, and it is not permissible to return the money to the estate. The amount must be withdrawn from the interest-based bank and deposited into an Islamic bank or a secure, Sharia-compliant investment. The bequest includes all good deeds, and the father's poor relatives have a greater right to these funds.