Sahih Muslim Book - 18, Hadith - 3652

حَدَّثَنَا يَحْيَى بْنُ يَحْيَى التَّمِيمِىُّ قَالَ قَرَأْتُ عَلَى مَالِكِ بْنِ أَنَسٍ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ أَنَّهُ طَلَّقَ امْرَأَتَهُ وَهْىَ حَائِضٌ فِى عَهْدِ رَسُولِ اللَّهِ -صلى الله عليه وسلم- فَسَأَلَ عُمَرُ بْنُ الْخَطَّابِ رَسُولَ اللَّهِ -صلى الله عليه وسلم- عَنْ ذَلِكَ فَقَالَ لَهُ رَسُولُ اللَّهِ -صلى الله عليه وسلم- « مُرْهُ فَلْيُرَاجِعْهَا ثُمَّ لْيَتْرُكْهَا حَتَّى تَطْهُرَ ثُمَّ تَحِيضَ ثُمَّ تَطْهُرَ ثُمَّ إِنْ شَاءَ أَمْسَكَ بَعْدُ وَإِنْ شَاءَ طَلَّقَ قَبْلَ أَنْ يَمَسَّ فَتِلْكَ الْعِدَّةُ الَّتِى أَمَرَ اللَّهُ عَزَّ وَجَلَّ أَنْ يُطَلَّقَ لَهَا النِّسَاءُ ».

It was narrated from Ibn 'Umar that he divorced his wife while she was menstruating, at the time of the Messenger of Allah (s.a.w). 'Umar bin Al-Khattab asked the Messenger of Allah (s.a.w) about that and the Messenger of Allah (s.a.w) said to him: "Tell him to take her back, then wait until she has become pure, then menstruated again, then become pure again. Then if he wishes he may keep her, or if he wishes he may divorce her before he has intercourse with her. That is the 'lddah (prescribed periods) for which Allah has enjoined the divorce of women."