It is reported that ‘Abdullâh b. Al-Mubârak – Allâh have mercy on him – said:

It is right that an intelligent person does not undervalue three [types of people]: the scholars, the rulers, and [his Muslim] brothers. Whoever undervalues the scholars will lose his afterlife, whoever undervalues the rulers will lose his worldly life, and whoever undervalues his brothers loses his good character and conduct.

Al-Dhahabî, Siyar A’lâm Al-Nubalâ`17:251.