Khula means to take off. In this context it means take off a marriage bond (by women). Allah (SWT) gave the husband the right to divorce and to balance the rights of the spouses; He gave the women the right to separate.
Allah (SWT) says:
"...And it is not lawful for you (men) to take back (from your wives) any of your Mahr (bridal money given by the husband to his wife at the time of marriage) which you have given them, except when both parties fear that they would be unable to keep the limits ordained by Allah (e.g. to deal with each other on a fair basis). Then if you fear that they would not be able to keep the limits ordained by Allah, then there is no sin on either of them if she gives back (the Mahr or a part of it) for her Al-Khul' (divorce)..." (Al-Baqarah 2:229)
Explaining this Hadith, Hafiz Ibn-e-Kathir writes: It is not lawful for you to tease your women so that you may take the dower back. However if the disagreement does not dissolve and the wife dislikes the husband and does not fulfill his rights, then she can obtain Khula by giving the dower back.
Narrated Ibn 'Abbas (RA): The wife of Thabit bin Qais came to the Prophet and said, "O Allah's Apostle! I do not blame Thabit for defects in his character or his religion, but I, being a Muslim, dislike to behave in un-Islamic manner (if I remain with him)." On that Allah's Apostle said (to her), "Will you give back the garden which your husband has given you (as Mahr)?" She said, "Yes." Then the Prophet said to Thabit, "O Thabit! Accept your garden, and divorce her once." (Sahih Al-Bukhari)
These Ahadith show that if the husband wants to divorce his wife, then he should not tease her to get the dower back. This is unlawful for him but if he does not want to divorce but the wife is bent on separation, then she should return the dower and seek separation. However, it is not lawful for a woman to obtain Khula without any reason. If she does on the persuasion of her parents or anyone else, then such a woman would not even get the scent of Paradise.
Thoban (RA) said: the Prophet (SAW) said:
"If any woman asks her husband for divorce without some strong reason, the odor of Paradise will be forbidden to her." (Sunan Abu Dawud)
In another Hadith, Abu Hurairah (RA) said: the Prophet of Allah (SAW) said:
"Those who seek Khula without any reason are hypocrites." (Musnad Ahmad)
It is not essential to seek Khula through court, the two parties can separate through mutual agreement. But if the husband does not agree then the wife can contact the court. As far as the question whether in case of Khula the amount more than dower can be demanded or not is concerned, the scholars differ on it. Some scholars regard it as unlawful. They quote the following Hadith as a proof. The Prophet (SAW) said:
"Don't demad the amount greater than the dower." (Ibn Majah)
The scholars have also differed on the matter whether Khula is a divorce or cancellation of Nikah. But the fact is whatever name you give it, its commands will remain the same. In case of Khula, the waiting period (Iddah) of a women is one menstruation period. When Rabi bint Masoodt obtained Khula from Thabit (RA), the Prophet (SAW) asked her to wait until one menstruation period before she could go her home. (An-Nissai, Abu Daud, Tirmizee)
Another thing worth mentioning is that in case of Khula, the husband does not have the right to touch his wife. Of course in that case it will negate the concept of Khula.
If the woman is pregnant than she does not have the right to marry again until the delivery because Allah (SWT) says:
"...And for those who are pregnant (whether they are divorced or their husbands are dead), their 'Iddah (prescribed period) is until they deliver (their burdens)..." (At-Talaq 65:4)
So the above discussion means that a wife buys the right of Khula by returning the dower.
Information From Voice of Islam Magazine