Musnad Abu Ya'la al-Mawsili 105:17

Al-Qawariri narrated to us, Abu Ahmad al-Zubayri narrated to us, al-'Ala' ibn Salih narrated to us, from 'Adi ibn Thabit, from Abu Rashid, who said: 'Ammar spoke and was brief. It was said to him: "You have said words, if only you had added more for us." He said: "Indeed, the Messenger of Allah (may Allah bless him and grant him peace) commanded us to shorten the sermons."