Narrator:Abdullāh ibn ‘Umar
أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا يَحْيَى، قَالَ حَدَّثَنَا عُبَيْدُ اللَّهِ، قَالَ حَدَّثَنِي نَافِعٌ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ
" لاَ تَصُومُوا حَتَّى تَرَوْهُ وَلاَ تُفْطِرُوا حَتَّى تَرَوْهُ فَإِنْ غُمَّ عَلَيْكُمْ فَاقْدُرُوا لَهُ "
It was narrated form Ibn 'Umar that the Prophet said:
"D not fast until you see it , and do not stop fasting until you see it, and if it is obscured from you (too cloudy), then work it out."
Reported by An-Nasa’i (No. 2122, 2121), Al-Bukhari (No. 1906, 1907), Muslim (No. 1080a, 1080e, 1080h), Abu Dawud (No. 2320), Malik (No. 633, 634), Ahmad (No. 4258, 5042) and Ad-Darimi (No. 1622, 1628).