Prohibition of Shighar
حَدَّثَنَا سُوَيْدُ بْنُ سَعِيدٍ، حَدَّثَنَا مَالِكُ بْنُ أَنَسٍ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ نَهَى رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ عَنِ الشِّغَارِ وَالشِّغَارُ أَنْ يَقُولَ الرَّجُلُ لِلرَّجُلِ زَوِّجْنِي ابْنَتَكَ أَوْ أُخْتَكَ عَلَى أَنْ أُزَوِّجَكَ ابْنَتِي أَوْ أُخْتِي . وَلَيْسَ بَيْنَهُمَا صَدَاقٌ .
It was narrated that: Ibn Umar said: “The Messenger of Allah (ﷺ) forbade Shighar. Shighar is when a man says to another man: 'Marry your daughter or sister to me, on condition that I will marry my daughter or sister to you,' and they do not give any dower (i.e. neither of them give other the dower).”