Anas said:

I never prayed behind an <i>imam</i>, 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.)

عَنْ أَنَسٍ قَالَ: مَا صَلَّيْتُ وَرَاءَ إِمَامٍ قَطُّ أَخَفَّ صَلَاةً وَلَا أَتَمَّ صَلَاةً مِنَ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَإِنْ كَانَ لَيَسْمَعُ بُكَاءَ الصَّبِيِّ فَيُخَفِّفُ مَخَافَةَ أَنْ تُفْتَنَ أمه