Sahih al-Bukhari 3219
Book 59: Beginning of Creation · Narrated by Ibn `Abbas
Arabic
حَدَّثَنَا إِسْمَاعِيلُ، قَالَ حَدَّثَنِي سُلَيْمَانُ، عَنْ يُونُسَ، عَنِ ابْنِ شِهَابٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ عُتْبَةَ بْنِ مَسْعُودٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " أَقْرَأَنِي جِبْرِيلُ عَلَى حَرْفٍ، فَلَمْ أَزَلْ أَسْتَزِيدُهُ حَتَّى انْتَهَى إِلَى سَبْعَةِ أَحْرُفٍ ".
English translation
Narrated Ibn `Abbas:Allah's Messenger (ﷺ) said, "Gabriel read the Qur'an to me in one way (i.e. dialect) and I continued asking him to read it in different ways till he read it in seven different ways
Reference: Sahih al-Bukhari 3219, Book of Beginning of Creation. English translation by Dr. Muhammad Muhsin Khan.