Sahih al-Bukhari
Sahih al-Bukhari 127
Whoever selected some people to teach them (religious) knowledge preferring them over others for fear that the others may not understand it
Arabic hadith text
حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُوسَى عَنْ مَعْرُوفِ بْنِ خَرَّبُوذٍ عَنْ أَبِي الطُّفَيْلِ عَنْ عَلِيٍّ بِذَلِكَ
Translation
Narrated Abu at-Tufail
Abu at-Tufail narrated the above mentioned statement of `Ali.