Sahih Muslim Book - 6, Hadith - 1902

وَحَدَّثَنِى حَرْمَلَةُ بْنُ يَحْيَى أَخْبَرَنَا ابْنُ وَهْبٍ أَخْبَرَنِى يُونُسُ عَنِ ابْنِ شِهَابٍ حَدَّثَنِى عُبَيْدُ اللَّهِ بْنُ عَبْدِ اللَّهِ بْنِ عُتْبَةَ أَنَّ ابْنَ عَبَّاسٍ حَدَّثَهُ أَنَّ رَسُولَ اللَّهِ -صلى الله عليه وسلم- قَالَ « أَقْرَأَنِى جِبْرِيلُ - عَلَيْهِ السَّلاَمُ - عَلَى حَرْفٍ فَرَاجَعْتُهُ فَلَمْ أَزَلْ أَسْتَزِيدُهُ فَيَزِيدُنِى حَتَّى انْتَهَى إِلَى سَبْعَةِ أَحْرُفٍ ». قَالَ ابْنُ شِهَابٍ بَلَغَنِى أَنَّ تِلْكَ السَّبْعَةَ الأَحْرُفَ إِنَّمَا هِىَ فِى الأَمْرِ الَّذِى يَكُونُ وَاحِدًا لاَ يَخْتَلِفُ فِى حَلاَلٍ وَلاَ حَرَامٍ.

Ibn 'Abbas narrated that the Messenger of Allah (s.a.w) said: "Jibril - peace be upon him - recited to me with one mode of recitation, but I asked him to recite it in another way, and I kept asking him for more, and he gave me more, until there were seven modes of recitation." Ibn Shihab said: "I heard that these seven modes of recitation are essentially one, and there is no difference between them concerning lawful and unlawful."