Is it permissible to stipulate the waiving of the deferred (part of the) dowry upon the husband's death?

The deferred dower (mu'akhkhar as-sadaq) is a debt owed by the husband, to be paid upon its due date. However, if the husband stipulates that it be waived if he dies before its due date, and the wife agrees to this at the time of the contract or thereafter, then she is bound by it, because this condition does not invalidate the contract. A woman may waive her right to the deferred dower after it has become due, based on the Almighty's saying: "But if they willingly give up to you anything of it, consume it in satisfaction and ease."