Mishkat al-Masabih 1981
Abul Bakhtari said:
We went out to perform the ‘umra , and when we encamped in the valley of Nakhla we tried to see the new moon. Some of the people said it was three nights old and others that it was two nights old. We then met Ibn ‘Abbas and told him we had seen the new moon, but that some of the people said it was three nights old and others that it was two nights old. He asked what night we had seen it, and when we told him we had seen it on such and such a night he said, “God’s messenger deferred it till the time it is seen, so it is to be reckoned as being on the night you saw it.” In a version he said: We saw the new moon of Ramadan when we were in Dhat ‘Irq* and we sent a man to Ibn ‘Abbas to enquire of him. He replied that God’s messenger had said, “God most high has deferred it till it is seen, but if the weather is cloudy observe the fast after the complete number of days have passed.” 
*Dhat 'Irq was near Nakhla, so this version is simply a little more precise than the other about were they were.

Muslim transmitted it.
وَعَنْ أَبِي الْبَخْتَرِيِّ قَالَ: خَرَجْنَا لِلْعُمْرَةِ فَلَمَّا نَزَلْنَا بِبَطْنِ نَخْلَةَ تَرَاءَيْنَا الْهِلَالَ. فَقَالَ بَعْضُ الْقَوْمِ: هُوَ ابْنُ ثَلَاثٍ. وَقَالَ بَعْضُ الْقَوْمِ: هُوَ ابْنُ لَيْلَتَيْنِ فَلَقِينَا ابْنَ عَبَّاسٍ فَقُلْنَا: إِنَّا رَأَيْنَا الْهِلَالَ فَقَالَ بَعْضُ الْقَوْمِ: هُوَ ابْنُ ثَلَاثٍ وَقَالَ بَعْضُ الْقَوْمِ: هُوَ ابْنُ لَيْلَتَيْنِ. فَقَالَ: أَيُّ لَيْلَةٍ رَأَيْتُمُوهُ؟ قُلْنَا: لَيْلَةَ كَذَا وَكَذَا. فَقَالَ: إِنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مَدَّهُ لِلرُّؤْيَةِ فَهُوَ لِلَيْلَةِ رَأَيْتُمُوهُ وَفِي رِوَايَةٍ عَنْهُ. قَالَ: أَهَلَلْنَا رَمَضَانَ وَنَحْنُ بِذَاتِ عِرْقٍ فَأَرْسَلْنَا رَجُلًا إِلَى ابْنِ عَبَّاسٍ يَسْأَلُهُ فَقَالَ ابْنُ عَبَّاسٍ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «إِن الله تَعَالَى قد أَمَدَّهُ لِرُؤْيَتِهِ فَإِنْ أُغْمِيَ عَلَيْكُمْ فَأَكْمِلُوا الْعِدَّةَ» . رَوَاهُ مُسلم