Imam Malik, may Allah have mercy on him, said: If a woman gives wealth to free herself, and then it becomes known that the husband was entirely unjust and the woman had no fault, rather the husband forcibly took her money by coercion, then the divorce will take effect upon the woman, and her wealth will be returned to her. This is what I have heard and, in my view, this is the ruling.
Imam Malik, may Allah have mercy on him, said: If a woman frees herself by giving more than what her husband gave her, there is nothing objectionable in it.
The slave woman of Safiyyah bint Abi Ubayd took khul‘ from her husband in exchange for all her wealth, and Abdullah ibn Umar (may Allah be pleased with them both) did not consider it objectionable.
Hadith Referenceموطا امام مالك رواية يحييٰ / كتاب الطلاق / 1166