Sahih Muslim , Book 18, Hadith 5 (In-Book) ⓘ

Ibn 'Umar (Allah be pleased with them) reported that he divorced his wife during the period of menses. 'Umar (Allah be, pleas'ed with him) asked Allah's Apostle, and he commanded him ('Abdullah b. 'Umar) to have her back and then allow her respite until she enters the period of the second menses, and then allow her respite until she is purified, then divorce her (finally) before touching her (having a sexual intercourse with her), for that is the prescribed period which Allah commanded (to be kept in view) for divorcing the women. When Ibn 'Umar (Allah be pleased with them) was asked about the person who divorces his wife in the state of menses, he said: If you pronounced one divorce or two, Allah's Messenger had commanded him to take her back, and then allow her respite until she enters the period of the second menses, and then allow her respite until she is purified, and then divorce her (finally) before touching her (having a sexual intercourse with her) ; and if you have pronounced (three divorces at one and the same time) you have in fact disobeyed your Lord with regard to what He commanded you about divorcing your wife. But she is however (finally separated from you).

وَحَدَّثَنِي زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا إِسْمَاعِيلُ، عَنْ أَيُّوبَ، عَنْ نَافِعٍ، أَنَّ ابْنَ عُمَرَ، طَلَّقَ امْرَأَتَهُ وَهْىَ حَائِضٌ فَسَأَلَ عُمَرُ النَّبِيَّ صلى الله عليه وسلم فَأَمَرَهُ أَنْ يَرْجِعَهَا ثُمَّ يُمْهِلَهَا حَتَّى تَحِيضَ حَيْضَةً أُخْرَى ثُمَّ يُمْهِلَهَا حَتَّى تَطْهُرَ ثُمَّ يُطَلِّقَهَا قَبْلَ أَنْ يَمَسَّهَا فَتِلْكَ الْعِدَّةُ الَّتِي أَمَرَ اللَّهُ أَنْ يُطَلَّقَ لَهَا النِّسَاءُ ‏.‏ قَالَ فَكَانَ ابْنُ عُمَرَ إِذَا سُئِلَ عَنِ الرَّجُلِ يُطَلِّقُ امْرَأَتَهُ وَهْىَ حَائِضٌ يَقُولُ أَمَّا أَنْتَ طَلَّقْتَهَا وَاحِدَةً أَوِ اثْنَتَيْنِ ‏.‏ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم أَمَرَهُ أَنْ يَرْجِعَهَا ثُمَّ يُمْهِلَهَا حَتَّى تَحِيضَ حَيْضَةً أُخْرَى ثُمَّ يُمْهِلَهَا حَتَّى تَطْهُرَ ثُمَّ يُطَلِّقَهَا قَبْلَ أَنْ يَمَسَّهَا وَأَمَّا أَنْتَ طَلَّقْتَهَا ثَلاَثًا فَقَدْ عَصَيْتَ رَبَّكَ فِيمَا أَمَرَكَ بِهِ مِنْ طَلاَقِ امْرَأَتِكَ ‏.‏ وَبَانَتْ مِنْكَ ‏.‏