"A Bedouin came to the Prophet and said: 'I have seen the crescent.' So he said: 'Do you testify that none has the right to be worshipped but Allah? Do you testify that Muhammad is the Messenger of Allah?' He said: 'Yes.' So he said: 'O Bilal! Announce to the people that they should fast tomorrow.'"  

جَاءَ أَعْرَابِيٌّ إِلَى النَّبِيِّ ﷺ فَقَالَ إِنِّي رَأَيْتُ الْهِلاَلَ قَالَ أَتَشْهَدُ أَنْ لاَ إِلَهَ إِلاَّ اللَّهُ أَتَشْهَدُ أَنَّ مُحَمَّدًا رَسُولُ اللَّهِ قَالَ نَعَمْ قَالَ يَا بِلاَلُ أَذِّنْ فِي النَّاسِ أَنْ يَصُومُوا غَدًا حَدَّثَنَا أَبُو كُرَيْبٍ حَدَّثَنَا حُسَيْنٌ الْجُعْفِيُّ عَنْ زَائِدَةَ عَنْ سِمَاكٍ نَحْوَهُ بِهَذَا الإِسْنَادِ