حَدَّثَنَا مُحَمَّدُ بْنُ بَكَّارِ بْنِ الرَّيَّانِ، حَدَّثَنَا الْوَلِيدُ، - يَعْنِي ابْنَ أَبِي ثَوْرٍ ح وَحَدَّثَنَا الْحَسَنُ بْنُ عَلِيٍّ، حَدَّثَنَا الْحُسَيْنُ، - يَعْنِي الْجُعْفِيَّ - عَنْ زَائِدَةَ، - الْمَعْنَى - عَنْ سِمَاكٍ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ، قَالَ جَاءَ أَعْرَابِيٌّ إِلَى النَّبِيِّ صلى الله عليه وسلم فَقَالَ إِنِّي رَأَيْتُ الْهِلاَلَ - قَالَ الْحَسَنُ فِي حَدِيثِهِ يَعْنِي رَمَضَانَ - فَقَالَ ‏"‏ أَتَشْهَدُ أَنْ لاَ إِلَهَ إِلاَّ اللَّهُ ‏"‏ ‏.‏ قَالَ نَعَمْ ‏.‏ قَالَ ‏"‏ أَتَشْهَدُ أَنَّ مُحَمَّدًا رَسُولُ اللَّهِ ‏"‏ ‏.‏ قَالَ نَعَمْ ‏.‏ قَالَ ‏"‏ يَا بِلاَلُ أَذِّنْ فِي النَّاسِ فَلْيَصُومُوا غَدًا ‏"‏ ‏.‏
Translation
Narrated Ikrimah

Once the people doubted the appearance of the moon of Ramadan, and intended neither to offer the tarawih prayer nor to keep fast. A bedouin came from al-Harrah and testified that he had sighted the moon. He was brought to the Prophet (ﷺ). He asked: Do you testify that there is no god but Allah, and that I am the Messenger of Allah? He said: Yes; and he testified that he had sighted the moon. He commanded Bilal who announced to the people to offer the tarawih prayer and to keep fast.