Compiled by Imam Muslim ibn al-Hajjaj
حَدَّثَنَا عَبْدُ بْنُ حُمَيْدٍ، أَخْبَرَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، أَنَّ النَّبِيَّ صلى الله عليه وسلم أَقْسَمَ أَنْ لاَ يَدْخُلَ عَلَى أَزْوَاجِهِ شَهْرًا - قَالَ الزُّهْرِيُّ - فَأَخْبَرَنِي عُرْوَةُ عَنْ عَائِشَةَ - رضى الله عنها - قَالَتْ لَمَّا مَضَتْ تِسْعٌ وَعِشْرُونَ لَيْلَةً أَعُدُّهُنَّ دَخَلَ عَلَىَّ رَسُولُ اللَّهِ صلى الله عليه وسلم - قَالَتْ بَدَأَ بِي - فَقُلْتُ يَا رَسُولَ اللَّهِ إِنَّكَ أَقْسَمْتَ أَنْ لاَ تَدْخُلَ عَلَيْنَا شَهْرًا وَإِنَّكَ دَخَلْتَ مِنْ تِسْعٍ وَعِشْرِينَ أَعُدُّهُنَّ فَقَالَ " إِنَّ الشَّهْرَ تِسْعٌ وَعِشْرُونَ " .
When twenty-nine nights were over, which I had counted, the Messenger of Allah (ﷺ) came to me (he came to me first of all). I said: Messenger of Allah, you had taken an oath that you would not come to us for a month, whereas you have come after twenty nine days which I have counted. Whereupon he said: The month may also consist of twenty-nine days.