It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Beware of suspicion, for suspicion is false speech. Do not look for others' faults, do not spy, do not compete with one another, do not envy one another, do not bear hatred, do not speak ill of anyone behind his back, and, O servants of Allah, be brothers."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الإقرار / 11457