Ibn ‘Umar said God’s Messenger prohibited <i>shighar</i>, which means that a man gives his daughter in marriage on condition that the other gives his daughter to him in marriage without any dower being paid by either. In a version by Muslim he said, “There is no <i>shighar</i> in Islam." (Bukhari and Muslim.)

وَعَنِ ابْنِ عُمَرَ: أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ نَهَى عَنْ الشِّغَارِ وَالشِّغَارُ: أَنْ يُزَوِّجَ الرَّجُلُ ابْنَتَهُ عَلَى أَنْ يُزَوِّجَهُ الْآخَرُ ابْنَتَهُ وَلَيْسَ بَيْنَهُمَا صَدَاقٌ