Sahih Muslim Book - 18, Hadith - 3661

وَحَدَّثَنِى عَلِىُّ بْنُ حُجْرٍ السَّعْدِىُّ حَدَّثَنَا إِسْمَاعِيلُ بْنُ إِبْرَاهِيمَ عَنْ أَيُّوبَ عَنِ ابْنِ سِيرِينَ قَالَ مَكَثْتُ عِشْرِينَ سَنَةً يُحَدِّثُنِى مَنْ لاَ أَتَّهِمُ أَنَّ ابْنَ عُمَرَ طَلَّقَ امْرَأَتَهُ ثَلاَثًا وَهْىَ حَائِضٌ فَأُمِرَ أَنْ يُرَاجِعَهَا فَجَعَلْتُ لاَ أَتَّهِمُهُمْ وَلاَ أَعْرِفُ الْحَدِيثَ حَتَّى لَقِيتُ أَبَا غَلاَّبٍ يُونُسَ بْنَ جُبَيْرٍ الْبَاهِلِىَّ. وَكَانَ ذَا ثَبَتٍ فَحَدَّثَنِى أَنَّهُ سَأَلَ ابْنَ عُمَرَ فَحَدَّثَهُ أَنَّهُ طَلَّقَ امْرَأَتَهُ تَطْلِيقَةً وَهْىَ حَائِضٌ فَأُمِرَ أَنْ يَرْجِعَهَا - قَالَ - قُلْتُ أَفَحُسِبَتْ عَلَيْهِ قَالَ فَمَهْ. أَوَإِنْ عَجَزَ وَاسْتَحْمَقَ

It was narrated that Ibn Sirin said: For twenty years those whom I trust narrated to me that Ibn 'Umar divorced his wife thrice while she was menstruating and he was told to take her back. I did not doubt them, but I did not hear the Hadith from anyone else either, until I met Abu Ghallab, Yunus bin Jubair Al-Bahili, who was very reliable. He told me that he asked Ibn 'Umar, who told him that he had divorced his wife with one divorce while she was menstruating, and he was commanded to take her back. He said: I said:" 'Was that counted as a divorce?' He said: 'Of course; it must be counted even if he failed and acted foolishly."