An-Nawawi’s Hadith No.35
On the authority of Abu Hurairah (Radhiallaho anha), who said : the Messenger of Allah (Sallallaahu ‘alaihi wasallam) said :
“Do not envy one another; do not inflate prices one to another; do not hate one another; do not turn away from one another; and do not undercut one another, but be you, O slaves of Allah, brothers. A Muslim is the brother of a Muslim: he neither oppresses him nor disgraces him, he neither lies to him nor does he hold him in contempt. Piety and righteousness is here – and he pointed to his breast three times. It is evil enough for a man to hold his brother Muslim in contempt. The whole of a Muslim for another Muslim is inviolable: his blood, his property, and his honor.”
Related by Muslim.