رِيَاضُ الصَّالِحِينَ
Riyad as-Salihin 228
The Book of Miscellany
Reverence towards the Sanctity of the Muslims
وَعَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ ، أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّه عَلَيْهِ وَسَلَّمَ قَالَ: إِذَا صَلَّى أَحَدُكُمْ لِلنَّاسِ، فَلْيُخَفِّفْ، فَإِنَّ فِيهِمُ الضَّعِيفَ وَالسَّقِيمَ وَالْكَبِيرَ. وَإِذَا صَلَّى لِنَفْسِهِ فَلْيُطَوِّلْ مَا شَاءَ ((مُتَّفَقٌ عَلَيْهِ)) . (10)
Abu Hurairah (May Allah bepleased with him) reported: Messenger of Allah (ﷺ) said, "When one of you leads the Salat, he should not prolong it because the congregation includes those who are feeble, ill or old". One version adds: "those who have to attend to work") While offering prayers alone, you may pray as long as you like". [Al-Bukhari and Muslim].
Riyad as-Salihin, 228