Chapter 46: The Book of Virtue, Enjoining Good Manners, and Joining of the Ties of Kinship
Abu Huraira reported Allah' s Messenger (ﷺ) as saying: Don' t nurse grudge and don' t bid him out for raising the price and don' t nurse aversion or enmity and don' t enter into a transaction when the others have entered into that transaction and be as fellow-brothers and servants of Allah. A Muslim is the brother of a Muslim. He neither oppresses him nor humiliates him nor looks down upon him. The piety is here, (and while saying so) he pointed towards his chest thrice. It is a serious evil for a Muslim that he should look down upon his brother Muslim. All things of a Muslim are inviolable for his brother in faith: his blood, his wealth and his honour.
Sahih Muslim 2564a