Musannaf Ibn Abi Shayba 3:2824

Ibn Numayr narrated to us, from al-‘Ala’ ibn Salih, from ‘Adi ibn Thabit, who said: Abu Rashid narrated to us. He said: ‘Ammar delivered a sermon to us and he was brief in the sermon. A man said: "You have said a healing statement, if only you had lengthened it." He said: "Indeed, the Messenger of Allah (may Allah bless him and grant him peace) forbade us from lengthening the sermon."