Sayyiduna Abu Hurayrah (may Allah be pleased with him) reports from the Prophet (peace and blessings be upon him): "When a servant speaks a word that pleases Allah, paying no heed to it, Allah raises his ranks by it; and when one speaks a word that angers Allah, paying no heed to it, Allah will cast him into Hell because of it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16665