Musnad Ahmad 1119:3

Abu Bakr al-Hanafi narrated to us, he said: al-Dahhak ibn Uthman narrated to us, from Bukayr ibn Abdullah ibn al-Ashajj, he said: Awf ibn Malik entered the Mosque of Bayt al-Maqdis, and with him was Dhu al-Kala’. Awf said to him: "Your cousin is with you." Dhu al-Kala’ said: "As for him, he is among the best or the most righteous of people." Awf said: "I bear witness that I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'No one shall deliver a sermon (qass) except an amir (commander), or one who is commanded (ma’mur), or a pretentious person (mutakallif).'"