Musnad Ahmad 30:1384

'Affan narrated to us, Wuhayb narrated to us, 'Abdullah ibn Tawus narrated to us, from his father, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Beware of suspicion, for suspicion is the most untruthful of speech. Do not seek out the faults of others, do not spy on one another, do not harbor hatred for one another, do not turn your backs on one another, and do not envy one another. And be, O servants of Allah, brothers."