Sahih al-Bukhari 127

(49) – باب مَنْ خَصَّ بِالْعِلْمِ قَوْمًا دُونَ قَوْمٍ كَرَاهِيَةَ أَنْ لاَ يَفْهَمُوا

(49) – Whoever selected some people to teach them (religious) knowledge preferring them over others for fear that the others may not understand it

Narrated Abu At-Tufail:

the above mentioned Statement of 'Ali.

حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُوسَى عَنْ مَعْرُوفِ بْنِ خَرَّبُوذٍ عَنْ أَبِي الطُّفَيْلِ عَنْ عَلِيٍّ بِذَلِكَ.

Sahih (Authentic)