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

Narrated Anas bin Malik: "Once Mu`adh was along with Allah's Messenger (sallallahu 'alaihi wa sallam) as a companion rider. Allah's Messenger (sallallahu 'alaihi wa sallam) said, "O Mu`adh bin Jabal." Mu`adh replied, "Labbaik and Sa`daik. O Allah's Messenger (sallallahu 'alaihi wa sallam)!" Again the Prophet (sallallahu 'alaihi wa sallam) said, "O Mu`adh!" Mu`adh said thrice, "Labbaik and Sa`daik, O Allah's Messenger (sallallahu 'alaihi wa sallam)!" Allah's Messenger (sallallahu 'alaihi wa sallam) said, "There is none who testifies sincerely that none has the right to be worshipped but Allah and Muhammad is his Apostle, except that Allah, will save him from the Hell-fire." Mu`adh said, "O Allah's Messenger (sallallahu 'alaihi wa sallam) ! Should I not inform the people about it so that they may have glad tidings?" He replied, "When the people hear about it, they will solely depend on it." Then Mu`adh narrated the above-mentioned Hadith just before his death, being afraid of committing sin (by not telling the knowledge).