وَعَنْ نَافِعٍ , عَنْ اِبْنِ عُمَرَ قَالَ : { نَهَى رَسُولُ اَللَّهِ - صلى الله عليه وسلم -عَنِ الشِّغَارِ ; وَالشِّغَارُ: أَنْ يُزَوِّجَ اَلرَّجُلُ اِبْنَتَهُ عَلَى أَنْ يُزَوِّجَهُ اَلْآخَرُ اِبْنَتَهُ , وَلَيْسَ بَيْنَهُمَا صَدَاقٌ } مُتَّفَقٌ عَلَيْهِ 1 .1 - صحيح . رواه البخاري ( 5112 ) ، ومسلم (1415).
Allah’s Messenger (ﷺ) prohibited Shighar, which means that a man gives his daughter in marriage on condition that the other gives his daughter to him in marriage without any dowry being paid by either.