The Muslim is the brother of the Muslim

On the authority of Abu Hurayra (may Allah be pleased with him), that the Messenger of Allah (may Allah bless him and grant him peace) said: "Do not envy one another, do not inflate prices against one another, do not hate one another, do not turn away from one another, and do not undercut one another in trade. Be servants of Allah, brothers to one another. A Muslim is the brother of a Muslim: he does not wrong him, does not fail him, does not lie to him and does not despise him. Piety is here” — and he pointed to his chest three times — “It is evil enough for a man to despise his Muslim brother. Every Muslim is inviolable to another Muslim: his blood, his property and his honour."

Related by Muslim.

[Muslim 2564]