Musnad Ahmad 30:609

'Abd al-Razzaq narrated to us, Dawud ibn Qays informed us, from Abu Sa'id, the freed slave of 'Abdullah ibn 'Amir, who said: I heard Abu Hurayrah saying: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Do not envy one another, do not outbid one another (to deceive), do not hate one another, do not turn your backs on one another, and let not one of you sell over the sale of his brother. And be, O servants of Allah, brothers. The Muslim is the brother of the Muslim; he does not wrong him, he does not forsake him, and he does not belittle him. Taqwa (piety/fear of Allah) is here—and he pointed with his hand to his chest three times. It is sufficient evil for a Muslim man to belittle his Muslim brother. Everything of a Muslim is sacred to another Muslim: his blood, his wealth, and his honor."