Sahih Bukhari Volume 1, Book 3, Hadith 90

حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ، قَالَ أَخْبَرَنَا سُفْيَانُ، عَنِ ابْنِ أَبِي خَالِدٍ، عَنْ قَيْسِ بْنِ أَبِي حَازِمٍ، عَنْ أَبِي مَسْعُودٍ الأَنْصَارِيِّ، قَالَ قَالَ رَجُلٌ يَا رَسُولَ اللَّهِ، لاَ أَكَادُ أُدْرِكُ الصَّلاَةَ مِمَّا يُطَوِّلُ بِنَا فُلاَنٌ، فَمَا رَأَيْتُ النَّبِيَّ صلى الله عليه وسلم فِي مَوْعِظَةٍ أَشَدَّ غَضَبًا مِنْ يَوْمِئِذٍ فَقَالَ ‏"‏ أَيُّهَا النَّاسُ، إِنَّكُمْ مُنَفِّرُونَ، فَمَنْ صَلَّى بِالنَّاسِ فَلْيُخَفِّفْ، فَإِنَّ فِيهِمُ الْمَرِيضَ وَالضَّعِيفَ وَذَا الْحَاجَةِ ‏"

Narrated By Abu Mas'ud Al-Ansari : Once a man said to Allah's Apostle "O Allah's Apostle! I may not attend the (compulsory congregational) prayer because so and so (the Imam) prolongs the prayer when he leads us for it. The narrator added: "I never saw the Prophet more furious in giving advice than he was on that day. The Prophet said, "O people! Some of you make others dislike good deeds (the prayers). So whoever leads the people in prayer should shorten it because among them there are the sick the weak and the needy (having some jobs to do)."