"When any one of you leads the people in prayer, let him make it short, for among them are the sick, the weak and the elderly. And when any one of you prays by himself, let him make it as long as he wishes." (Using translation from Nasāʾī 823)  

عَنِ النَّبِيِّ ﷺ قَالَ «إِذَا صَلَّى أَحَدُكُمْ بِالنَّاسِ فَلْيُخَفِّفْ فَإِنَّ فِيهِمُ السَّقِيمُ وَالضَّعِيفُ وَالْكَبِيرُ وَإِذَا صَلَّى أَحَدُكُمْ لِنَفْسِهِ فَلْيُطَوِّلْ مَا شَاءَ»  

The Messenger of Allah ﷺ was among those whose prayers was brief and perfect. (Using translation from Muslim 469b)  

أَنَّ النَّبِيَّ ﷺ كَانَ «أَخَفَّ النَّاسِ صَلَاةً فِي تَمَامٍ»  

"I stand in prayer, then I hear a child crying, so I make my prayer brief, because I do not want to cause hardship for his mother." (Using translation from Nasāʾī 825)  

عَنِ النَّبِيِّ ﷺ قَالَ «إِنِّي لَأَقُومُ فِي الصَّلَاةِ فَأَسْمَعُ بُكَاءَ الصَّبِيِّ فَأَتَجَوَّزُ فِي صَلَاتِي كَرَاهِيَةَ أَنْ أَشُقَّ عَلَى أُمِّهِ»