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tabarani:11786 – Yaʿqūb b. Isḥāq al-Mukharrimī > Muslim b. Ibrāhīm > Ḥāzim b. Ibrāhīm > Simāk b. Ḥarb > ʿIkrimah > Ibn ʿAbbās

[Machine] People used to rely on the sight of the crescent to determine the start of the month during the time of the Messenger of Allah ﷺ. Then, a bedouin came and testified that he had seen it, so the Prophet ﷺ asked him, "Do you testify that there is no god but Allah and that I am the Messenger of Allah?" The bedouin replied, "Yes." Upon hearing this, the Prophet ﷺ ordered Bilal to announce, "Indeed, fasting is to be observed tomorrow."  

الطبراني:١١٧٨٦ – حَدَّثَنَا يَعْقُوبُ بْنُ إِسْحَاقَ الْمُخَرِّمِيُّ ثنا مُسْلِمُ بْنُ إِبْرَاهِيمَ ثنا حَازِمُ بْنُ إِبْرَاهِيمَ عَنْ سِمَاكِ بْنِ حَرْبٍ عَنْ عِكْرِمَةَ عَنِ ابْنِ عَبَّاسٍ قَالَ

تَمَارَى النَّاسُ فِي الْهِلَالِ عَلَى عَهْدِ رَسُولِ اللهِ ﷺ فَجَاءَ أَعْرَابِيٌّ فَشَهِدَ أَنَّهُ رَآهُ فَقَالَ النَّبِيُّ ﷺ «تَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللهُ وَأَنِّي رَسُولُ اللهِ؟» قَالَ نَعَمْ فَأَمَرَ النَّبِيُّ ﷺ بِلَالًا فَنَادَى «إِنَّ الصَّوْمَ غَدًا»  

See similar narrations below:

Collected by Dārimī, Ibn Ḥibbān
darimi:1734 – ʿIṣmah b. al-Faḍl

A bedouin came to the Prophet ﷺ and said: I have sighted the moon. Al-Hasan added in his version: that is, of Ramadan. He asked: Do you testify that there is no god but Allah? He replied: Yes. He again asked: Do you testify that Muhammad is the Messenger of Allah? He replied: Yes. and he testified that he had sighted the moon. He said: Bilal, announce to the people that they must fast tomorrow. (Using translation from Abū Dāʾūd 2340)   

الدارمي:١٧٣٤ – حَدَّثَنِي عِصْمَةُ بْنُ الْفَضْلِ حَدَّثَنَا حُسَيْنٌ الْجُعْفِيُّ عَنْ زَائِدَةَ عَنْ سِمَاكٍ عَنْ عِكْرِمَةَ عَنْ ابْنِ عَبَّاسٍ قَالَ

جَاءَ أَعْرَابِيٌّ إِلَى النَّبِيِّ ﷺ وَقَالَ إِنِّي رَأَيْتُ الْهِلَالَ فَقَالَ «أَتَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللَّهُ وَأَنِّي رَسُولُ اللَّهِ؟» قَالَ نَعَمْ قَالَ «يَا بِلَالُ نَادِ فِي النَّاسِ فَلْيَصُومُوا غَدًا»  

ذِكْرُ إِجَازَةِ شَهَادَةِ الشَّاهِدِ الْوَاحِدِ إِذَا كَانَ عَدْلًا عَلَى رُؤْيَةِ هِلَالِ رَمَضَانَ

ibnhibban:3446 – Abū Yaʿlá > Abū Bakr b. Abū Shaybah > al-Ḥusayn b. ʿAlī > Zāʾidah > Simāk b. Ḥarb > ʿIkrimah > Ibn ʿAbbās

"A Bedouin come to the Prophet and said; 'I have sighted the crescent tonight.' He said: 'Do you bear witness that there is none worthy of worship except Allah, and that Messenger?' He said: 'Yes.' He said: 'O Bilal, announce to the people that they should fast tomorrow. "' (Using translation from Nasāʾī 2113)   

ابن حبّان:٣٤٤٦ – أَخْبَرَنَا أَبُو يَعْلَى قَالَ حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ قَالَ حَدَّثَنَا الْحُسَيْنُ بْنُ عَلِيٍّ عَنْ زَائِدَةَ عَنْ سِمَاكِ بْنِ حَرْبٍ عَنْ عِكْرِمَةَ عَنِ ابْنِ عَبَّاسٍ قَالَ

جَاءَ إِلَى النَّبِيِّ ﷺ أَعْرَابِيٌّ فَقَالَ أَبْصَرْتُ الْهِلَالَ اللَّيْلَةَ فَقَالَ «تَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللَّهُ وَأَنَّ مُحَمَّدًا عَبْدُهُ وَرَسُولُهُ» قَالَ نَعَمْ قَالَ «قُمْ يَا فُلَانُ فَنَادِ فِي النَّاسِ فَلْيَصُومُوا غَدًا» وَأَخْبَرَنَاهُ أَبُو يَعْلَى مَرَّةً أُخْرَى وَقَالَ «قُمْ يَا بِلَالُ»