قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ : " إِذَا أَمَّ أَحَدُكُمْ لِلنَّاسِ، فَلْيُخَفِّفِ الصَّلاةَ، فَإِنَّ فِيهِمُ الْكَبِيرَ وَفِيهِمُ الضَّعِيفَ وَفِيهِمُ السَّقِيمَ، وَإِنْ قَامَ وَحْدَهُ فَلْيُطِلْ صَلاتَهُ مَا شَاءَ "
And the Messenger of Allah, peace and blessings be upon him, said: "When any of you leads the people in prayer, he should make it brief, for among the congregation are some who are elderly, some who are weak, and some who are ill. But if he prays alone, he may prolong the prayer as much as he wishes."