In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Iyaad Bin Himaar [radiyallaahu-anhu] said: The Messenger [sallal-laahi-alayhi-wasallam] stood amongst us one day and addressed (us), so he said: Indeed Allaah has revealed to me that you must be humble, so that no one boasts over another and no one oppresses another. [Saheeh Muslim: Hadeeth Number: 2865]
[Indeed Allaah has revealed to me that you must be humble]- Meaning: Everyone should be humble towards the other and not elevate himself above another [person]; rather he [a person] should place him [i.e. the other person] in the same rank as himself or honours him more. And it was from the customary behaviour of the Salaf [may Allaah have mercy upon them] for one amongst them to treat someone younger than him like his own son and someone older than him like his own father, and someone similar to him like his own brother. So he looks at the one older than him with honour and reverence, the one younger than him with compassion and mercy and the one similar to him with equality-none transgresses against the other. This is from the affairs that are obligatory upon a person to characterise himself with- humble in the presence of Allaah and towards his Muslim brothers.
[An Excerpt from Sharh Riyaadus-Saaliheen- by Imaam Muhammad Ibn Saaleh Al-Uthaymeen (rahimahullaah): Number: 602 slightly paraphrased]