كتاب الصوم
7  
Fasting
(2a)
Chapter: Seeing the New Moon - Section 1
(1)
باب رؤية الهلال - الفصل الأول
Mishkat al-Masabih 1971
Ibn ‘Umar reported God’s messenger as saying, “We are an unlettered people who can neither write nor count. The month is thus and thus and thus,” drawing in his thumb when he said it the third time.* Then he said, “The month is thus and thus and thus,” meaning a complete thirty days. He meant alternately twenty-nine and thirty. *Spreading out the ten fingers the first two times and nine the third time. (Bukhari and Muslim.)
وَعَنِ ابْنِ عُمَرَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «أَنَا أمة أُميَّة لَا تكْتب وَلَا تحسب الشَّهْرُ هَكَذَا وَهَكَذَا وَهَكَذَا» . وَعَقَدَ الْإِبْهَامَ فِي الثَّالِثَةِ. ثُمَّ قَالَ: «الشَّهْرُ هَكَذَا وَهَكَذَا وَهَكَذَا» . يَعْنِي تَمَامَ الثَّلَاثِينَ يَعْنِي مَرَّةً تِسْعًا وَعِشْرِينَ وَمرَّة ثَلَاثِينَ "
  مُتَّفَقٌ عَلَيْهِ   (الألباني) حكم   :
Reference : Mishkat al-Masabih 1971
In-book reference : Book 7, Hadith 15