صحيح مسلم
Sahih Muslim
كتاب الصيام
The Book of Fasting
باب وُجُوبِ صَوْمِ رَمَضَانَ لِرُؤْيَةِ الْهِلاَلِ وَالْفِطْرِ لِرُؤْيَةِ الْهِلاَلِ وَأَنَّهُ إِذَا غُمَّ فِي أَوَّلِهِ أَوْ آخِرِهِ أُكْمِلَتْ عِدَّةُ الشَّهْرِ ثَلاَثِينَ يَوْمًا:
Chapter: The obligation to fast Ramadan when the crescent is sighted, and to break the fast when the crescent is sighted, and that if it is cloudy at the beginning or end of the month, then the month should be completed as thirty days.
Hadith 1081
This hadith is listed as number 2515 in Maktaba Shamila
حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ سَلَّامٍ الْجُمَحِيُّ ، حَدَّثَنَا الرَّبِيعُ يَعْنِي ابْنَ مُسْلِمٍ ، عَنْ مُحَمَّدٍ وَهُوَ ابْنُ زِيَادٍ ، عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ ، أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ ، قَالَ : " صُومُوا لِرُؤْيَتِهِ وَأَفْطِرُوا لِرُؤْيَتِهِ ، فَإِنْ غُمِّيَ عَلَيْكُمْ فَأَكْمِلُوا الْعَدَدَ " .
Abu Hurairah (RA) reported Allah's Messenger (ﷺ) as saying: Observe fast on sighting it (the new moon) and break (fast) on sighting it (the new moon), but if the sky is cloudy for you, then complete the number (of thirty).
