أَخْبَرَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، قَالَ حَدَّثَنَا عَبْدُ الرَّحْمَنِ، عَنْ سُفْيَانَ، عَنِ الأَسْوَدِ بْنِ قَيْسٍ، عَنْ سَعِيدِ بْنِ عَمْرٍو، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " إِنَّا أُمَّةٌ أُمِّيَّةٌ لاَ نَكْتُبُ وَلاَ نَحْسِبُ الشَّهْرُ هَكَذَا وَهَكَذَا وَهَكَذَا " . ثَلاَثًا حَتَّى ذَكَرَ تِسْعًا وَعِشْرِينَ .
It was narrated from Ibn 'Umar that the Prophet said: "We are an unlettered Ummah, we do not use astronomical counting or computation. The month is like this, and this, and this," he did three times, showing it as twenty-nine. Translation Not Available
Book Ref: Sunan An Nisai Book 22 Hadith 2140
Web Ref: Sunan An Nisai Vol 3 Book 22 Hadith 2142