Sayyiduna Abu al-Darda' (may Allah be pleased with him) reports this saying of the Prophet (peace and blessings be upon him): "Any man whose intercession becomes an obstacle to one of the hudud (prescribed punishments) of Allah Almighty remains continually under the displeasure of Allah Almighty until he desists. Any man who shows anger against a Muslim in a dispute about which he has no knowledge has stubbornly opposed the right of Allah Almighty and shown eagerness for His displeasure; upon such a man is the curse of Allah Almighty, which continues until the Day of Resurrection. And any man who spreads a word against a Muslim man while that man is innocent of it, intending thereby to revile him in this world, it is binding upon Allah Almighty to melt him in the Fire of Hell on the Day of Resurrection until he brings something by which he can get out of (the punishment for) what he said."
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأحكام / 7040