Command him to take her back, then divorce her when she is pure or she is pregnant.  

أَنَّهُ طَلَّقَ امْرَأَتَهُ وَهْىَ حَائِضٌ فَذَكَرَ ذَلِكَ عُمَرُ لِلنَّبِيِّ ﷺ فَقَالَ مُرْهُ فَلْيُرَاجِعْهَا ثُمَّ لْيُطَلِّقْهَا طَاهِرًا أَوْ حَامِلاً  

Ibn ‘Umar said that he divorced his wife while she was menstruating. ‘Umar mentioned the matter to the Prophet ﷺ. He (the Prophet) said “Order him, he must take her back and divorce her when she is purified (from menstrual discharge) or she is pregnant.”  

أَنَّهُ طَلَّقَ امْرَأَتَهُ وَهِيَ حَائِضٌ فَذَكَرَ ذَلِكَ عُمَرُ لِلنَّبِيِّ ﷺ فَقَالَ رَسُولُ اللَّهِ ﷺ مُرْهُ فَلْيُرَاجِعْهَا ثُمَّ لْيُطَلِّقْهَا إِذَا طَهُرَتْ أَوْ وَهِيَ حَامِلٌ  

His father divorced his wife during her menses, so Umar asked the Prophet about that and he said: "Tell him to take her back, then let him divorce her while she is pure or pregnant."  

أَنَّهُ طَلَّقَ امْرَأَتَهُ فِي الْحَيْضِ فَسَأَلَ عُمَرُ النَّبِيَّ ﷺ فَقَالَ مُرْهُ فَلْيُرَاجِعْهَا ثُمَّ لْيُطَلِّقْهَا طَاهِرًا أَوْ حَامِلاً  

he divorced his wife when she was menstruating, and 'Umar mentioned that to the Prophet ﷺ. He said: "Tell him to take her back then divorce her when she is pure (not menstruating) or pregnant."  

أَنَّهُ طَلَّقَ امْرَأَتَهُ وَهِيَ حَائِضٌ فَذَكَرَ ذَلِكَ عُمَرُ لِلنَّبِيِّ ﷺ فَقَالَ مُرْهُ فَلْيُرَاجِعْهَا ثُمَّ لِيُطَلِّقْهَا وَهِيَ طَاهِرٌ أَوْ حَامِلٌ  

Ibn ‘Umar said that he divorced his wife while she was menstruating. ‘Umar mentioned the matter to the Prophet ﷺ. He (the Prophet) said “Order him, he must take her back and divorce her when she is purified (from menstrual discharge) or she is pregnant.” (Using translation from Abū Dāʾūd 2181)   

أَنَّهُ طَلَّقَ امْرَأَتَهُ وَهِيَ حَائِضٌ فَذَكَرَ ذَلِكَ عُمَرُ لِلنَّبِيِّ ﷺ فَقَالَ رَسُولُ اللهِ ﷺ لِيُرَاجِعْهَا حَتَّى تَطْهُرَ ثُمَّ لِيُطَلِّقْهَا إِنْ شَاءَ  

His father divorced his wife during her menses, so Umar asked the Prophet about that and he said: "Tell him to take her back, then let him divorce her while she is pure or pregnant." (Using translation from Tirmidhī 1176)  

أَنَّهُ طَلَّقَ امْرَأَتَهُ وَهِيَ حَائِضٌ فَسَأَلَ عُمَرُ النَّبِيَّ ﷺ فَقَالَ مُرْهُ فَلْيُرَاجِعْهَا ثُمَّ لِيُطَلِّقْهَا طَاهِرًا أَوْ حَامِلًا  

he divorced his wife when she was menstruating, and 'Umar mentioned that to the Prophet ﷺ. He said: "Tell him to take her back then divorce her when she is pure (not menstruating) or pregnant." (Using translation from Ibn Mājah 2023)  

أَنَّهُ طَلَّقَ امْرَأَتَهُ فِي الْحَيْضِ فَذَكَرَ ذَلِكَ عُمَرُ لِلنَّبِيِّ ﷺ فَقَالَ مُرْهُ فَلْيُرَاجِعْهَا ثُمَّ لِيُطَلِّقْهَا وَهِيَ طَاهِرٌ أَوْ حَامِلٌ  

[Machine] I divorced my wife while she was menstruating, and Umar mentioned that to the Messenger of Allah ﷺ , and he said, "Tell him to take her back."  

طَلَّقْتُ امْرَأَتِي وَهِيَ حَائِضٌ فَذَكَرَ عُمَرُ ذَلِكَ لِرَسُولِ اللهِ ﷺ فَقَالَ «مُرْهُ فَلْيُرَاجِعْهَا»  

he divorced his wife when she was menstruating, and 'Umar mentioned that to the Prophet ﷺ. He said: "Tell him to take her back then divorce her when she is pure (not menstruating) or pregnant." (Using translation from Ibn Mājah 2023)  

أَنَّهُ طَلَّقَ امْرَأَتَهُ وَهِيَ حَائِضٌ فَذُكِرَ ذَلِكَ لِلنَّبِيِّ ﷺ فَقَالَ «مُرْهُ فَلْيُرَاجِعْهَا ثُمَّ لِيُطَلِّقْهَا وَهِيَ طَاهِرٌ أَوْ حَامِلٌ»  

he divorced his wife when she was menstruating, and 'Umar mentioned that to the Prophet ﷺ. He said: "Tell him to take her back then divorce her when she is pure (not menstruating) or pregnant." (Using translation from Ibn Mājah 2023)   

أَنَّهُ طَلَّقَ امْرَأَتَهُ وَهِيَ حَائِضٌ فَذَكَرَ ذَلِكَ عُمَرُ لِلنَّبِيِّ ﷺ فَقَالَ مُرْهُ فَلْيُرَاجِعْهَا ثُمَّ لِيُطَلِّقْهَا طَاهِرًا أَوْ حَامِلًا  

"مرْهُ فَليُراجِعْهَا ثم لِيُطَلِّقْهَا طَاهِرًا أَوْ حَامِلًا".