مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 1129
Prayer
The Imam's duty - Section 1
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
Anas said: 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.)
Mishkat al-Masabih, 1129مُتَّفق عَلَيْهِ (الألباني)