Musnad Ahmad 28:239

Abu al-Nadr narrated to us, al-Faraj narrated to us, from Abdullah ibn Amir, from Amr ibn Shu’ayb, from his father, from his grandfather, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "No one shall tell stories (give sermons/narrate) except an amir (a leader), or one who is commanded (by a leader), or a show-off (hypocrite)." I said to him: "It only used to reach us that it was 'or a pretentious person (mutakallif)'?" He said: "This is how I heard the Prophet (peace and blessings of Allah be upon him) say it."