To take back one's wife while in her menses.
حَدَّثَنَا حَجَّاجٌ، حَدَّثَنَا يَزِيدُ بْنُ إِبْرَاهِيمَ، حَدَّثَنَا مُحَمَّدُ بْنُ سِيرِينَ، حَدَّثَنِي يُونُسُ بْنُ جُبَيْرٍ، سَأَلْتُ ابْنَ عُمَرَ فَقَالَ طَلَّقَ ابْنُ عُمَرَ امْرَأَتَهُ وَهْىَ حَائِضٌ، فَسَأَلَ عُمَرُ النَّبِيَّ صلى الله عليه وسلم فَأَمَرَهُ أَنْ يُرَاجِعَهَا، ثُمَّ يُطَلِّقَ مِنْ قُبُلِ عِدَّتِهَا، قُلْتُ فَتَعْتَدُّ بِتِلْكَ التَّطْلِيقَةِ قَالَ أَرَأَيْتَ إِنْ عَجَزَ وَاسْتَحْمَقَ.
Narrated Yunus Ibn Jubair: Ibn `Umar divorced his wife while she was having her menses. `Umar asked the Prophet (ﷺ) who said, "Order him (your son) to take her back, and then divorced her before her period of the 'Iddah has elapsed." I asked Ibn `Umar, "Will that divorce (during the menses) be counted?" He replied, "If somebody behaves foolishly (will his foolishness be an excuse for his misbehavior)?"