Abu Hurairah, radiyallahu 'anhu, reported that the Messenger of Allah, sallallahu 'alayhi wasallam, said:
\"Do not be envious of one another; do not artificially inflate prices against one another; do not hate one another; do not shun one another; and do not undercut one another in business transactions; 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. Piety is here - and he pointed to his chest three times. It is evil enough for a Muslim to hold his brother Muslim in contempt. All things of a Muslim are inviolable for another Muslim: his blood, his property and his honour.\" [Muslim]