(Imām Bukhārī narrates): 'Abdullāh ibn Yūsuf narrated to us, he said: Imām Mālik informed us, from Abī al-Zinād, from al-A'raj, from Abū Hurairah, may Allāh be pleased with him, that the Messenger of Allāh ﷺ said:
When any one of you leads the people in prayer, let him pray with brevity, because among them there are the weak, the sick, and the elderly. And when any one of you prays his own prayer, let him make it as long as he wishes.
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، قَالَ: أَخْبَرَنَا مَالِكٌ، عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ قَالَ: «إِذَا صَلَّى أَحَدُكُمْ لِلنَّاسِ، فَلْيُخَفِّفْ، فَإِنَّ مِنْهُمُ الضَّعِيفَ وَالسَّقِيمَ وَالكَبِيرَ، وَإِذَا صَلَّى أَحَدُكُمْ لِنَفْسِهِ فَلْيُطَوِّلْ مَا شَاءَ»
Reference: Sahih Al Bukhari 703