Ibn 'Umar said:

"I divorced my wife when she was menstruating. 'Umar went to the Prophet and told him about that. The Prophet ﷺ said: 'Tell him to take her back, then when she becomes pure, if he wants to, let him divorce her.'" I said to Ibn 'Umar: "Did that count as one divorce?" He said: "Why not? What do you think if some becomes helpless and behaves foolishly."

أَخْبَرَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، قَالَ حَدَّثَنَا مُحَمَّدٌ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ قَتَادَةَ، قَالَ سَمِعْتُ يُونُسَ بْنَ جُبَيْرٍ، قَالَ سَمِعْتُ ابْنَ عُمَرَ، قَالَ طَلَّقْتُ امْرَأَتِي وَهِيَ حَائِضٌ فَأَتَى النَّبِيَّ ﷺ عُمَرُ فَذَكَرَ لَهُ ذَلِكَ فَقَالَ النَّبِيُّ ﷺ " مُرْهُ أَنْ يُرَاجِعَهَا فَإِذَا طَهُرَتْ - يَعْنِي - فَإِنْ شَاءَ فَلْيُطَلِّقْهَا " . قُلْتُ لاِبْنِ عُمَرَ فَاحْتَسَبْتَ مِنْهَا فَقَالَ مَا يَمْنَعُهَا أَرَأَيْتَ إِنْ عَجَزَ وَاسْتَحْمَقَ .