He—may Allah Most High have mercy on him—was asked:

A man entered into a marriage arrangement with a young woman. For years he supported her financially and made payments to her. When he resolved to consummate the marriage, he discovered that her father had married her to someone else. What is the ruling?

He replied:

It is authentically established that the Prophet, may Allah bless him and grant him peace, said:

“A Muslim is the brother of another Muslim. It is not permissible for a Muslim to propose marriage to a woman to whom his brother has already proposed, to supplant his brother in negotiations for a purchase, or to sell over his brother’s sale.”

If a man proposes marriage to a woman and the person responsible for contracting her marriage—such as a father with binding authority in marriage—has accepted him, no one else may propose to her. How much more serious, then, is the case when they have accepted him, had witnesses attest to the preliminary marriage arrangement preceding the contract, received gifts from him, and allowed a long time to pass! These people have undoubtedly committed a prohibited act for which they deserve punishment. But is the second marriage contract valid or void? The scholars hold two views:

The first—which is one of the two views within the schools of Mālik and Ahmad—is that the second man’s marriage contract is void. She must therefore be separated from him and returned to the first man.

The second is that the marriage is valid. This is the position of Abū Hanīfah and al-Shāfiʿī. Those who committed the prohibited act are to be punished, and everything taken from the first man must be returned to him.

The first view is more in keeping with the Quran and Sunnah.