Sahih Muslim 818
Sahih Muslim · Book 6: The Book of Prayer - Travellers · The clarification that the Qur’an was revealed in seven ahruf (modes of recitation), and clarifying its meaning
حَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ ، وَعَبْدُ بْنُ حُمَيْدٍ ، قَالاَ أَخْبَرَنَا عَبْدُ الرَّزَّاقِ ، أَخْبَرَنَا مَعْمَرٌ ، عَنِ الزُّهْرِيِّ ، كَرِوَايَةِ يُونُسَ بِإِسْنَادِهِ .
This hadith has been transmitted by Zuhri.