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كتاب الاستئذان
79  
Asking Permission
(24)
Chapter: How to write a letter to the people of the Scripture
(24)
باب كَيْفَ يُكْتَبُ الْكِتَابُ إِلَى أَهْلِ الْكِتَابِ
Sahih al-Bukhari 6260

Narrated Abu Sufyan bin Harb:

that Heraclius had sent for him to come along with a group of the Quraish who were trading in Sha'm, and they came to him. Then Abu Sufyan mentioned the whole narration and said, "Heraclius asked for the letter of Allah's Messenger (ﷺ) . When the letter was read, its contents were as follows: 'In the name of Allah, the Beneficent, the Merciful. From Muhammad, Allah's slave and His Apostle to Heraclius, the Chief of Byzantines: Peace be upon him who follows the right path (guidance)! Amma ba'du (to proceed )...' (See Hadith No 6, Vol 1 for details)

حَدَّثَنَا مُحَمَّدُ بْنُ مُقَاتِلٍ أَبُو الْحَسَنِ، أَخْبَرَنَا عَبْدُ اللَّهِ، أَخْبَرَنَا يُونُسُ، عَنِ الزُّهْرِيِّ، قَالَ أَخْبَرَنِي عُبَيْدُ اللَّهِ بْنُ عَبْدِ اللَّهِ بْنِ عُتْبَةَ، أَنَّ ابْنَ عَبَّاسٍ، أَخْبَرَهُ أَنَّ أَبَا سُفْيَانَ بْنَ حَرْبٍ أَخْبَرَهُ أَنَّ هِرَقْلَ أَرْسَلَ إِلَيْهِ فِي نَفَرٍ مِنْ قُرَيْشٍ وَكَانُوا تِجَارًا بِالشَّأْمِ، فَأَتَوْهُ فَذَكَرَ الْحَدِيثَ قَالَ ثُمَّ دَعَا بِكِتَابِ رَسُولِ اللَّهِ صلى الله عليه وسلم فَقُرِئَ فَإِذَا فِيهِ ‏ "‏ بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ، مِنْ مُحَمَّدٍ عَبْدِ اللَّهِ وَرَسُولِهِ إِلَى هِرَقْلَ عَظِيمِ الرُّومِ، السَّلاَمُ عَلَى مَنِ اتَّبَعَ الْهُدَى، أَمَّا بَعْدُ ‏"‏‏.‏
Reference : Sahih al-Bukhari 6260
In-book reference : Book 79, Hadith 34
USC-MSA web (English) reference : Vol. 8, Book 74, Hadith 277
  (deprecated numbering scheme)