In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Iyaad Bin Himaar [radiyallaahu-anhu] reported that Allaah’s Messenger [sallal laahu alayhi wasallam] addressed them and said, “Verily, Allaah has revealed to me that you must be humble towards one another, so that no one oppresses another or boasts to another”.
This great hadeeth is from the Jawaami Al-Kalim [i.e. a short statement that contains a vast meaning]. In this hadeeth, the Prophet [sallal laahu alayhi Wasallam] guides us to humbleness, whose opposite is haughtiness, transgression, belittling the people and mocking at them. As for the humble person, he that one who has Islamic manners and deals with his Muslim brothers based on Islamic brotherhood- neither transgresses against them nor mocks at them; neither belittles their rights nor treats them in an evil manner through speech or action. You always see him forgoing his rights out of humility to Allaah [The Blessed and Exalted].
The heart is the place where humility resides and it manifests on the limbs through good speech, good deeds and good dealings with others, and thus a person earns abundant reward. When a Muslim possesses this quality and refrains from exalting himself above the people, then indeed he fights against its opposites, such as belittling others, looking down on the people, treating them in an evil manner through speech and action, and other than that; rather he establishes the rights of brotherhood based on Eemaan just as Islaam calls to this great quality.
This hadeeth guides one to abandon transgression and to be humble. It is [not permissible for] anyone to transgress against another person- neither through speech nor deeds- meaning: Do not transgress against him and thus oppress him. Do not [violate] his honour, blood and wealth, and through this brotherhood based on Eemaan is established, the Muslim actualises this great quality and thus Allaah raises his status.
[An Excerpt from ”At-leeqaat Al-Maleehah Alaa Sisilah Al-Ahaadeeth As-Saheehah. Vol 1. page 92. slightly paraphrased]