Musnad Ahmad 652:14

Sulayman ibn Dawud narrated to us, Shu'bah informed us, from Simak, who said: I heard al-Nu'man delivering a sermon, and he was wearing a *khamisah* (a square-patterned garment) of his. He said: I truly heard the Messenger of Allah, peace and blessings of Allah be upon him, delivering a sermon while he was saying: "I have warned you of the Fire." So much so that if a man were at such-and-such a place, he would have heard his voice.