Ash-Shiqaq (the breach between the man and his wife).

Sahih al-Bukhari · Book 68 · Hadith 5278

حَدَّثَنَا أَبُو الْوَلِيدِ، حَدَّثَنَا اللَّيْثُ، عَنِ ابْنِ أَبِي مُلَيْكَةَ، عَنِ الْمِسْوَرِ بْنِ مَخْرَمَةَ، قَالَ سَمِعْتُ النَّبِيَّ صلى الله عليه وسلم يَقُولُ ‏"‏ إِنَّ بَنِي الْمُغِيرَةِ اسْتَأْذَنُوا فِي أَنْ يَنْكِحَ عَلِيٌّ ابْنَتَهُمْ، فَلاَ آذَنُ ‏"‏‏.‏

Narrated Al-Miswar bin Makhrama Az-Zuhri: I heard the Prophet (ﷺ) saying, "Banu Al-Mughira have asked my leave to let `Ali marry their daughter, but I give no leave to this effect."