If they agree on khula’, does the husband have the right to change his mind?
Question

                If a man agrees to grant his wife a divorce by khula’, on the basis that she will return the mahr to him, then before she gives him the mahr the husband wants to change his mind, does he have the right to do that?
Praise be to Allah.
    If he has indeed divorced her by khula’, in the sense that 
    the marriage has been annulled and there is nothing left to be done except 
    handing over the compensation (i.e., the mahr), then he has no choice in the 
    matter, even if he has not yet taken back the mahr. But if they have agreed 
    to khula’ without yet having the marriage annulled, rather they have agreed 
    that he will let her go when she hands over the mahr, then this does not 
    mean that the marriage has been annulled, rather it is promise to annul it. 
    So if it has not yet been annulled, then he has the right to change his mind 
    and not do that which he had intended. If he had said, “If you give me the 
    mahr you will be free (I will give you khula’),” then according to the 
    Hanbali madhhab he does not have the right to change his mind. But according 
    to Shaykh al-Islam Ibn Taymiyah, if he has not yet taken back the mahr then 
    he has the right to change his mind. In order to be on the safe side, if the 
    latter scenario has taken place and they want to get back together, they 
    should make a new marriage contract so as to put themselves beyond any area 
    of scholarly dispute.