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