أَخْبَرَنَا مَحْمُودُ بْنُ غَيْلاَنَ، قَالَ حَدَّثَنَا وَكِيعٌ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ مُحَمَّدِ بْنِ عَبْدِ الرَّحْمَنِ، مَوْلَى طَلْحَةَ عَنْ سَالِمِ بْنِ عَبْدِ اللَّهِ، عَنِ ابْنِ عُمَرَ، أَنَّهُ طَلَّقَ امْرَأَتَهُ وَهِيَ حَائِضٌ فَذَكَرَ ذَلِكَ لِلنَّبِيِّ صلى الله عليه وسلم فَقَالَ ‏"‏ مُرْهُ فَلْيُرَاجِعْهَا ثُمَّ لْيُطَلِّقْهَا وَهِيَ طَاهِرٌ أَوْ حَامِلٌ ‏"‏ ‏.‏

It was narrated from Ibn 'Umar that he divorced his wife while she was menstruating. He mentioned that to the Prophet and he said: "Tell him to take her back, then divorce her while she is pure (not menstruating) or pregnant." Translation Not Available

Book Ref: Sunan An Nisai Book 27 Hadith 3397
Web Ref:  Sunan An Nisai Vol 4 Book 27 Hadith 3426