Abu Huraira reported God’s Messenger as saying, “When one of you leads the people in prayer he should be brief, for among them are the sick, the weak, and the aged. But when one of you prays by himself he may be as long as he likes.”
Abu Qatada reported God’s Messenger as saying, “When I begin the prayer. I intend to make it long, but I hear a boy crying and shorten my prayer, being aware of his mother’s emotion because of his crying.”
Qais b. Abu Hazim said Abu Mas'ud told him of a man saying, “I swear by God, Messenger of God, that I keep away from the Morning Prayer on account of so and so, because he keeps us so long.” I never saw God’s Messenger more angry when giving an exhortation than he was that day. He said, “Some of you are scaring people away, so whoever of you leads the people in prayer must be brief, for among them are the weak, the aged, and people who have business to do.”
I never prayed behind an imam, who was more brief or more perfect in his prayer than the Prophet. If he heard a boy crying he would shorten the prayer for fear his mother might be distressed.