Sahih al-Bukhari 5046
صحيح البخاري#5046Sahihحَدَّثَنَا عَمْرُو بْنُ عَاصِمٍ، حَدَّثَنَا هَمَّامٌ، عَنْ قَتَادَةَ، قَالَ سُئِلَ أَنَسٌ كَيْفَ كَانَتْ قِرَاءَةُ النَّبِيِّ صلى الله عليه وسلم. فَقَالَ كَانَتْ مَدًّا. ثُمَّ قَرَأَ بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ، يَمُدُّ بِبِسْمِ اللَّهِ، وَيَمُدُّ بِالرَّحْمَنِ، وَيَمُدُّ بِالرَّحِيمِ.
Narrated Qatada:Anas was asked, "How was the recitation (of the Qur'an) of the Prophet?' He replied, "It was characterized by the prolongation of certain sounds." He then recited: In the Name of Allah, the Most Beneficent, the Most Merciful prolonging the pronunciation of 'In the Name of Allah, 'the most Beneficent,' and 'the Most Merciful
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 66:70