All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
The majority of scholars are of the opinion that khul' (divorce initiated by the wife) is permissible on what the spouses agree upon, even if it is more than the mahr (the dowry).
Some of them are of the view that he should not take from her more than what he gave her, and the opinion that we adopt in fatwa is the first opinion, based on the saying of Allah the Almighty (which means): {...then there is no blame upon either of them concerning that by which she ransoms herself....} [Quran 2: 229].
But it is better for him not to take from her more than what he gave her. Ibn Qudamah said in Al-Mughni: “It is not desirable for him to take more than what he gave her.”
Allah knows best.