Proposing to someone's sister and offering his daughter as a wife instead of paying Mahr

Q: A man who has no wife now wants to marry a woman in exchange for his daughter, i.e., he wants his daughter to marry a man and to marry this man’s sister in return, because he is poor and has no money to pay to get married. Is it permissible for him to marry in exchange for his daughter’s hand in marriage instead of money? What is the best thing for him to do?

A: If the questioner means by his question to compare between marrying a woman in exchange for his daughter marrying the woman’s brother and marrying a woman by giving her money, there is no comparison between the two. That a man marries a woman in return of giving his daughter in marriage as an exchange deal between him and another is Haram (prohibited) and it is known as Shighar marriage (exchange of daughters or sisters for marriage with no mandatory gift to a bride from her groom), which the Prophet (peace be upon him) forbade. It was narrated by Nafi‘ on the authority of Ibn ‘Umar (may Allah be pleased with them both) that The Messenger of Allah (peace be upon him) forbade Shighar marriage. A Shighar marriage is one in which two men exchange their daughters in marriage with no Mahr (mandatory gift to a bride from her groom). (Agreed upon by Al-Bukhari and Muslim) As for him marrying for money, there is nothing wrong in doing so. Accordingly, it is clear that comparing between something that is Haram and something that is permissible is inappropriate. However, if he meant by the comparison whether it was better for him to marry a woman whose Waliy (a legally accountable person acting for a woman regarding marriage) (Part No. 18; Page No. 426) wants to marry his daughter and for them to give money [to the brides. Ed] or to marry another woman and give her money, it is preferable and safer for him to step away from blame to marry another woman. This is because, if he marries the woman whose Waliy wants to marry his daughter, he might be lenient over his daughter’s Mahr in return for the Waliy being lenient with him in the Mahr he asks for his daughter. They may also risk falling into the suspicion of entering into Shighar marriage. It was been authentically reported that the Prophet (peace be upon him) said, “What is Halal (lawful) is clear and what is Haram (prohibited) is clear, and between them lie doubtful matters which many people do not know about. So anyone who avoids the doubtful matters has protected their faith and their honor, and anyone who falls into the doubtful matters, falls into that which is Haram.” He (peace be upon him) also said, “Leave that which makes you doubt for that which does not make you doubt.” May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.