Musnad Ahmad 774:14

'Abd al-Rahman narrated to us, from Sufyan, from 'Abd al-'Aziz ibn Rufay', from Tamim ibn Tarfah, from 'Adi ibn Hatim, who said: Two men came to the Messenger of Allah, may Allah bless him and grant him peace. One of them delivered the testimony (tashahhud) and said: "Whoever obeys Allah and His Messenger has been rightly guided, and whoever disobeys them..." The Messenger of Allah, may Allah bless him and grant him peace, said: "You are a bad speaker; stand up."