Ibn ʿUmar bin Al-Khattab divorced his wife during her menses. Messenger of Allah ﷺ ordered him to take her back till she became clean, and when she got another period while she was with him, she should wait till she became clean again and only then, if he wanted to divorce her, he could do so before having sexual relations with her. And that is the period Allah has fixed for divorcing women. Whenever ʿAbdullah (bin ʿUmar) was asked about that, he would say to the questioner, "If you divorced her thrice, she is no longer lawful for you unless she marries another man (and the other man divorces her in his turn).' Ibn ʿUmar further said, 'Would that you (people) only give one or two divorces, because the Prophet ﷺ has ordered me so."  

أَنَّ ابْنَ عُمَرَ بْنِ الْخَطَّابِ ؓ طَلَّقَ امْرَأَةً لَهُ وَهْىَ حَائِضٌ تَطْلِيقَةً وَاحِدَةً فَأَمَرَهُ رَسُولُ اللَّهِ ﷺ أَنْ يُرَاجِعَهَا ثُمَّ يُمْسِكَهَا حَتَّى تَطْهُرَ ثُمَّ تَحِيضَ عِنْدَهُ حَيْضَةً أُخْرَى ثُمَّ يُمْهِلَهَا حَتَّى تَطْهُرَ مِنْ حَيْضِهَا فَإِنْ أَرَادَ أَنْ يُطَلِّقَهَا فَلْيُطَلِّقْهَا حِينَ تَطْهُرُ مِنْ قَبْلِ أَنْ يُجَامِعَهَا فَتِلْكَ الْعِدَّةُ الَّتِي أَمَرَ اللَّهُ أَنْ تُطَلَّقَ لَهَا النِّسَاءُ وَكَانَ عَبْدُ اللَّهِ إِذَا سُئِلَ عَنْ ذَلِكَ قَالَ لأَحَدِهِمْ إِنْ كُنْتَ طَلَّقْتَهَا ثَلاَثًا فَقَدْ حَرُمَتْ عَلَيْكَ حَتَّى تَنْكِحَ زَوْجًا غَيْرَهُ وَزَادَ فِيهِ غَيْرُهُ عَنِ اللَّيْثِ حَدَّثَنِي نَافِعٌ قَالَ ابْنُ عُمَرَ لَوْ طَلَّقْتَ مَرَّةً أَوْ مَرَّتَيْنِ فَإِنَّ النَّبِيَّ ﷺ أَمَرَنِي بِهَذَا  

When 'Abdullah was asked about it, he said to one of them: If you have divorced your wife with one pronouncement or two (then you can take her back), for Messenger of Allah ﷺ commanded me to do it; but if you have divorced her with three pronouncements, then she is forbidden for you until she married another husband, and you disobeyed Allah in regard to the divorce of your wife what He had commanded you. (Muslim said: The word" one divorce" used by Laith is good.)  

أَنَّهُ طَلَّقَ امْرَأَةً لَهُ وَهْىَ حَائِضٌ تَطْلِيقَةً وَاحِدَةً فَأَمَرَهُ رَسُولُ اللَّهِ ﷺ أَنْ يُرَاجِعَهَا ثُمَّ يُمْسِكَهَا حَتَّى تَطْهُرَ ثُمَّ تَحِيضَ عِنْدَهُ حَيْضَةً أُخْرَى ثُمَّ يُمْهِلَهَا حَتَّى تَطْهُرَ مِنْ حَيْضَتِهَا فَإِنْ أَرَادَ أَنْ يُطَلِّقَهَا فَلْيُطَلِّقْهَا حِينَ تَطْهُرُ مِنْ قَبْلِ أَنْ يُجَامِعَهَا فَتِلْكَ الْعِدَّةُ الَّتِي أَمَرَ اللَّهُ أَنْ يُطَلَّقَ لَهَا النِّسَاءُ وَزَادَ ابْنُ رُمْحٍ فِي رِوَايَتِهِ وَكَانَ عَبْدُ اللَّهِ إِذَا سُئِلَ عَنْ ذَلِكَ قَالَ لأَحَدِهِمْ أَمَّا أَنْتَ طَلَّقْتَ امْرَأَتَكَ مَرَّةً أَوْ مَرَّتَيْنِ فَإِنَّ رَسُولَ اللَّهِ ﷺ أَمَرَنِي بِهَذَا وَإِنْ كُنْتَ طَلَّقْتَهَا ثَلاَثًا فَقَدْ حَرُمَتْ عَلَيْكَ حَتَّى تَنْكِحَ زَوْجًا غَيْرَكَ وَعَصَيْتَ اللَّهَ فِيمَا أَمَرَكَ مِنْ طَلاَقِ امْرَأَتِكَ قَالَ مُسْلِمٌ جَوَّدَ اللَّيْثُ فِي قَوْلِهِ تَطْلِيقَةً وَاحِدَةً  

I divorced my wife during the lifetime of Messenger of Allah ﷺ when she was in the state of menses. 'Umar (Allah be pleased with him) made a mention of it to Messenger of Allah ﷺ, whereupon he said: Command him to take her back and leave her (in that state) until she is purified. Then (let her) enter the period of second menses, and when she is purified, then divorce her (finally) before having a sexual intercourse with her, or retain her (finally). That is the 'Idda (the prescribed period) which Allah commanded (to be kept in view) while divorcing the women. 'Ubaidullah reported: I said to Nafi': What became of that divorce (pronounced within 'Idda)? He said: It was as one which she counted. (Using translation from Muslim 1471c)   

طَلَّقْتُ امْرَأَتِي عَلَى عَهْدِ رَسُولِ اللهِ ﷺ وَهِيَ حَائِضٌ فَذَكَرَ ذَلِكَ عُمَرُ ؓ لِرَسُولِ اللهِ ﷺ فَقَالَ رَسُولُ اللهِ ﷺ مُرْهُ فَلْيُرَاجِعْهَا حَتَّى تَطْهُرَ ثُمَّ تَحِيضَ حَيْضَةً أُخْرَى فَإِذَا طَهُرَتْ فَلْيُطَلِّقْهَا إِنْ شَاءَ قَبْلَ أَنْ يُجَامِعَهَا أَوْ يُمْسِكْهَا فَإِنَّهَا الْعِدَّةُ الَّتِي أَمَرَ اللهُ تَعَالَى أَنْ تُطَلَّقَ لَهَا النِّسَاءُ فَقُلْتُ لِنَافِعٍ مَا صَنَعَتِ التَّطْلِيقَةُ؟ قَالَ وَاحِدَةً اعْتَدَّتْ بِهَا