عَنْ يَحْيَى بْنِ عَبْدِ الرَّحْمَنِ بْنِ حَاطِبٍ قَالَ: قَالَ عَبْدُ اللَّهِ بْنُ عُمَرَ رَضِيَ اللَّهُ عَنْهُمَا: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ: ((الشَّهْرُ تِسْعٌ وَعِشْرُونَ)) وَصَفَّقَ بِيَدَيْهِ مَرَّتَيْنِ، ثُمَّ صَفَّقَ الثَّالِثَةَ وَقَبَضَ إِبْهَامَهُ، (وَفِي رِوَايَةٍ: فَذَكَرَ ذَلِكَ لِعَائِشَةَ) فَقَالَتْ عَائِشَةُ رَضِيَ اللَّهُ عَنْهَا: غَفَرَ اللَّهُ لِأَبِي عَبْدِ الرَّحْمَنِ، إِنَّهُ وَهِمَ، إِنَّمَا هَجَرَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ نِسَاءَهُ شَهْرًا، فَنَزَلَ لِتِسْعٍ وَعِشْرِينَ، فَقَالُوا: يَا رَسُولَ اللَّهِ! إِنَّكَ نَزَلْتَ لِتِسْعٍ وَعِشْرِينَ، فَقَالَ: ((إِنَّ الشَّهْرَ يَكُونُ تِسْعًا وَعِشْرِينَ))
It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: The month is (29) days. Then, to explain, he struck one hand on the other twice and on the third time folded his thumb. In another narration: When people mentioned this to Sayyida Aisha (may Allah be pleased with her), she said: May Allah forgive Abu Abdur Rahman, Sayyiduna Ibn Umar (may Allah be pleased with him), he made a mistake. The real matter was that the Messenger of Allah (peace and blessings be upon him) had separated himself from his wives for a month, and on the (29th) day he came down (from the upper room). People said to him (peace and blessings be upon him): You have come down on the twenty-ninth day (even though you had separated for a month)? He (peace and blessings be upon him) said: Indeed, this month is (29) days.