حَدَّثَنَا عَبْدُ الرَّزَّاقِ قَالَ أَخْبَرَنَا مَعْمَرٌ عَنِ الزُّهْرِيِّ عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ عُتْبَةَ عَنِ ابْنِ عَبَّاسٍ عَنْ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ أَقْرَأَنِي جِبْرِيلُ عَلَى حَرْفٍ فَرَاجَعْتُهُ فَلَمْ أَزَلْ أَسْتَزِيدُهُ وَيَزِيدُنِي فَانْتَهَى إِلَى سَبْعَةِ أَحْرُفٍ قَالَ الزُّهْرِيُّ وَإِنَّمَا هَذِهِ الْأَحْرُفُ فِي الْأَمْرِ الْوَاحِدِ وَلَيْسَ يَخْتَلِفُ فِي حَلَالٍ وَلَا حَرَامٍ
مسند امام احمد بن حنبل · Hadith 2860
It was narrated from Ibn 'Abbas (RA) that the Messenger of Allah (PBUH) said: "Jibreel taught me one mode of recitation (harf) and i asked for another one, and I kept asking for more and he gave me more, until it ended with seven modes of recitation." Az-Zuhri said: These modes of recitation only affect the recitation, they do not change anything with regard to halal and haram.
Sanad
حَدَّثَنَا عَبْدُ الرَّزَّاقِ قَالَ أَخْبَرَنَا مَعْمَرٌ عَنِ الزُّهْرِيِّ عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ عُتْبَةَ عَنِ ابْنِ عَبَّاسٍ