Sahih Muslim Book 4, Hadith Number 940.

Chapter : Recitation in the night prayer.

Abu Mas’ud al-Ainsari reported: A person came to the Messenger of Allah (may peace be upon him) and said: I keep away from the morning prayer on account of such and such (a man), because; he keeps us so long. I never saw God’s Messenger (may peace be upon him) more angry when giving an exhortation than he was that day. He said: O people, some of you are scaring people away. So whoever of you leads the people in prayer he must be brief, for behind him are the weak, the aged, and the people who have (argent) business to attend.