Al-Hāfidh Ibn Hajr (rahimahullāh) said:
987: Narrated Nāfi’ from Ibn ‘Umar (radiyallāhu ‘anhumā) who said:
“Allaah’s Messenger (salallāhu ‘alaihi wasallam) prohibited ‘shighār’ – and ‘shighār’ is when a man gives his daughter in marriage on the condition that the other man gives to him, his daughter in marriage in exchange without any dowry being paid by either.”
Reported by Bukhaaree, no. 5112. Muslim, no. 1415, 57. And Bukhaaree (6960) said that the explanation of the meaning of ‘shighār’ was from Naafi`.
Shaikh Sālih al-Fawzān (hafidhahullāh) said:
This contains another type of invalid marriage, and that is what is known as “Shighaar”. The shighār marriage as has been explained by the narrator himself, and that is Naafi`, the freed slave of Ibn ‘Umar stated: That a man marries his daughter to another man on the condition that the other man marries off his daughter back to him, without any dowry being given by either side. So a woman is exchanged for a woman. So this is the explanation of the narrator, Naafi`. It is said that it is the explanation of Ibn `Umar, others said it is the explanation of Maalik Ibn Anas, and others have said it is the explanation of Allaah’s Messenger (salallāhu ‘alaihi wasallam).
If it is the saying of the Prophet (salallāhu ‘alaihi wasallam), then then it cannot be questioned. And if it is the explanation of the narrator, then the narrator is more acquainted regarding what he is narrating, so regardless the explanation is accepted and correct. So this marriage is invalid because the Messenger prohibited it. And this prohibition proves its invalidity.
The wisdom behind its prohibition is to remove harm from women. In this case, the guardian has judged concerning her, and he decided her affair. So he did not marry her off except due to what he wanted and desired himself, and not based upon her wishes. He marries her off in an incompetent manner, and due to his own greed to marry the daughter of another man in exchange. So by way of this, he has caused harm to the woman that he is the guardian over. And if this type of marriage takes place without the paying of dowries to the women, then the woman has merely become a product of exchange, and that is not allowed and invalid. However, if there is a payment of dowries to both women, each woman receiving a dowry in accordance to what is customary for a woman of her stature, then what is understood from this narration and its explanation is that the marriage is valid due to the removal of any harm coming upon the women. This is the opinion of the majority of the scholars: So long as the dowries are paid in accordance to what is customary to both women, then there is nothing to prevent the validity of the marriage (as long as the women have consented), even if there is something of an exchange therein. However, what is correct is that if there is some harm that will come upon the woman, even if dowries have been agreed upon, then the marriage is still invalid because the dowry may be used as a tool of deception to reach what the guardian himself wants which is his own marriage – and that is not permitted. This is what is referred to by the common people as the marriage of exchange. So the wisdom behind its forbiddance is to fulfil and honour rights that are in the benefit of the woman.
Adapted from volume 4: Kitābun-Nikāh (The Book of Marriage) from Shaikh Sālih al-Fawzān’s explanation of Bulūgh Al-Marām min Adillatil-Ahkām of Al-Hāfidh Ahmad Ibn ‘Ali Ibn Hajr Al-Asqalāni (born 773H, died 852H), entitled Tas-heel al-Ilmām bi-fiqhil-Ahādeeth min Bulūghil-Marām and is printed in seven volumes.