Full Sharh — Sahih Muslim 2530
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا غُنْدَرٌ، عَنْ شُعْبَةَ، ح وَحَدَّثَنَا ابْنُ الْمُثَنَّى، وَابْنُ، بَشَّارٍ قَالاَ حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، أَخْبَرَنَا شُعْبَةُ، عَنْ عَمْرِو بْنِ مُرَّةَ، قَالَ سَمِعْتُ أَبَا الْبَخْتَرِيِّ، قَالَ أَهْلَلْنَا رَمَضَانَ وَنَحْنُ بِذَاتِ عِرْقٍ فَأَرْسَلْنَا رَجُلاً إِلَى ابْنِ عَبَّاسٍ - رضى الله عنهما - يَسْأَلُهُ فَقَالَ ابْنُ عَبَّاسٍ - رضى الله عنهما - قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِنَّ اللَّهَ قَدْ أَمَدَّهُ لِرُؤْيَتِهِ فَإِنْ أُغْمِيَ عَلَيْكُمْ فَأَكْمِلُوا الْعِدَّةَ " .
English Translation
Abu'l-Bakhtari reported:We saw the new moon of Ramadan as we were at Dhit-i-'Irq. We sent a man to Ibn Abbas (Allah be pleased with both of them) to ask him (whether the sighting of a small moon had something of the nature of defect in it). Upon this Ibn 'Abbas (Allah be pleased with both of them) said that the Messenger of Allah (ﷺ) had said: Verily Allah deferred its sight, but if (the new moon) is hidden from you, then, complete its number (thirty)
Source
Sahih Muslim(صحيح مسلم)
The Book of Fasting
Hadith Number
2530