The clarification that the Qur’an was revealed in seven ahruf (modes of recitation), and clarifying its meaning Sahih Muslim 818 c
حَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، وَعَبْدُ بْنُ حُمَيْدٍ، قَالاَ أَخْبَرَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، كَرِوَايَةِ يُونُسَ بِإِسْنَادِهِ
Translation
This hadith has been transmitted by Zuhri.