What is the ruling on a deferred mahr?

Question : Honorable Shaykh, is a woman's deferred mahr valid? Is it a debt upon the man that he is obligated to pay? If the man dies before paying it, is it paid from his estate? Is zakah obligatory on it?

Answer : The deferred mahr. It is permissible and there is no harm in it, based on the saying of Allah the Exalted: Fulfilling the contract includes fulfilling it and what was stipulated in it.
Because what is stipulated in the contract is among the attributes of the contract, and fulfilling the contract is general, covering both its essence and its attributes. Based on this, we say that if a man stipulates the deferral of the mahr or part of it, there is no harm, but when is it due?
If a specific, known term was set for it, by saying, "Defer the mahr for a period of five years," then it does not become due until the completion of the term, which is five years. If it was not deferred, then it becomes due upon separation, if a separation occurs between the husband and wife by divorce, open sinfulness, or death, then it becomes due, and it is a debt upon the husband that he is liable for after its term arrives during his lifetime.
And after death, like all other debts. As for zakah, it is obligatory on the woman regarding it if the husband is wealthy. If he is poor, then zakah is not obligatory on her regarding it, and...
This issue, which I mean the stipulation of deferring the mahr, what is your opinion? If you were to suggest to people, would there not be a reduction in the mahr? There is a reduction in the mahr, and I wish people would do this, instead of the husband going and incurring debt, and burdening his back with money and debts, he makes the debt upon the woman. But what do you say if the deferral occurs and the man enters his home and asks his wife to waive the mahr?
If she waived it, is this permissible or not? Yes, it is permissible if she is of sound mind. If he said, "Either you waive the mahr that is in my liability, or I will divorce you," and she waived it, is it waived or not? It is not waived, because she did not waive it at that time except under coercion, and it is not permissible to coerce her to...