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. (Bukhari and Muslim.)
Reported by Al-Bukhari (No. 708). Cited in Mishkat al-Masabih (No. 1129).
Abu Qatādah and Anas ibn Mālik (may Allah be pleased with both of them) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Verily, I would stand up for (congregational) prayer intending to prolong it, but I hear the crying of an infant, so I shorten my prayer lest I make…
"إني لأقوم إلى الصلاة، وأريد أن أطول فيها ، فأسمع بكاء الصبي، فأتجوز في صلاتي كراهية أن أشق على أمه"