Khula explained.

The case that established it

The wife of Thabit ibn Qays came to the Prophet ﷺ and said she found no fault in her husband's character or his religion, but that she could not remain with him without failing in her own religion. She was not alleging cruelty, neglect or any wrong. She simply could not continue.

The Prophet ﷺ asked one question: would she return the garden Thabit had given her as mahr. She said yes. He instructed Thabit to accept it and separate from her.

Read the exchange for what it does not contain. No demand that she prove harm. No attempt to talk her out of it. No inquiry into whether her reason was good enough. One question about the mahr, and it was done.

How khula differs from talaq

Talaq is pronounced by the husband and costs the wife nothing; her mahr remains hers. Khula is sought by the wife and she returns the mahr, or an amount agreed between them. The Qur'an permits precisely this exchange where both fear they cannot keep within the limits Allah set.

The consequences differ too. A khula ends the marriage without consuming one of the husband's pronouncements of divorce, and the waiting period is shorter, which is the majority position based on the narration of the same case. Where a husband refuses a khula outright, a wife may petition an Islamic court or judicial authority, which can dissolve the marriage; that is faskh, a separate route.

What may be asked of her

The Qur'an sanctions the return of what was given. It does not sanction using the wife's wish to leave as leverage to extract more than that. A husband who demands beyond the mahr in order to release her is doing the thing the verse's surrounding passages repeatedly forbid: keeping a woman to harm her.

Two things routinely get confused here. Her mahr is returnable in a khula. Her own property, her earnings, and anything she owned before or acquired during the marriage are not, and never were.

A caution, stated fairly

There are narrations warning severely against a wife seeking separation with no cause at all, and they are widely quoted. They are also routinely deployed against women who have a serious cause, as a way of shaming them into staying. The case of Thabit's wife is the corrective: her stated reason was that she could not continue, and it was accepted without interrogation.

This page describes what khula is. It is not a ruling on any particular marriage. A woman considering it should speak to a scholar who can hear the specifics, and where there is abuse, to people who can keep her safe first.