Mishkat al-Masabih 13 Marriage كتاب النكاح 66

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

Ibn ‘Umar said God’s Messenger 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 dower being paid by either. In a version by Muslim he said, “There is no shighar in Islam.” (Bukhari and Muslim.)