Musnad Ahmad 190:1

Abu Mu’awiyah narrated to us, Muhammad bin ‘Amr bin ‘Alqamah al-Laythi narrated to us, from his father, from his grandfather ‘Alqamah, from Bilal bin al-Harith al-Muzani, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, a man may speak a word that pleases Allah the Almighty, not thinking that it would reach what it reached, yet Allah the Almighty writes for him His pleasure by it until the Day of Resurrection. And indeed, a man may speak a word that angers Allah the Almighty, not thinking that it would reach what it reached, yet Allah the Almighty writes against him His anger by it until the Day of Resurrection." He said: So ‘Alqamah used to say: "How much speech have I been prevented from by the hadith of Bilal bin al-Harith."