Musnad Ahmad 26:123

Abu Dawud al-Hafari ‘Umar ibn Sa‘d narrated to us, Sufyan narrated to us, from Ibrahim ibn Muhajir, from Muslim al-Batin, from Abu ‘Abd al-Rahman, from ‘Abdullah, who said: The Messenger of Allah (may Allah bless him and grant him peace) spoke, then his face changed, then he said: "Something like this, or close to this."