Members of the Advisory Council of `Umar (radiyallahu `anhu), the second Caliph of Islam, were always the `Ulamaa’ (the learned in religion) whether they are old or of young age.
Abu Huraira (radiyallahu `anhu) reported that the Messenger of Allah (sallallahu `alayhi wa sallam) said: "Anyone who is most versed in Allah’s Book should act as an Imaam for the people; but if they are equally versed in reciting it, then the one who has most knowledge regarding the Sunnah; if they are equal regarding the Sunnah, then the earliest of them to emigrate; if they emigrated at the same time, then the oldest of them."
In another version it is reported:
"No man must lead another in Prayer where the latter has authority, or sit in his place of honour in his house, without his permission." (Muslim transmitted it.)
Jaabir (radiyallahu `anhu) said:
"Allah’s Messenger (sallallahu `alayhi wa sallam) had each pair of those killed at the Ghazwa of Uhud wrapped in a single garment and asked which of them knew more of the Holy Qur’an. When one of them was pointed out to him, he had him put first in the side of the grave." (Bukhari transmitted it.)
Abu Musa Al-Ash`ari (radiyallahu `anhu) reported that Allah’s Messenger (sallallahu `alayhi wa sallam) said:
"It is out of reverence to Allah in respecting an aged Muslim, and the one who commits the Qur'an to memory and does not exaggerate pronouncing its letters nor forgets it after memorizing, and to respect the just ruler". (Abu Dawud)