Abu Hazim said:“Sahl bin Sa’d As-Sa’idi used to give preference to the young to lead his people in prayer. It was said to him: “Do you do that, when you have such seniority (in Islam)?” He said: “I heard the Messenger of Allah (ﷺ) say: ‘The Imam is responsible. If he does well, then he will have the reward and so will they, but if he does badly, then that will be counted against him but not against them.’”
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا سَعِيدُ بْنُ سُلَيْمَانَ، حَدَّثَنَا عَبْدُ الْحَمِيدِ بْنُ سُلَيْمَانَ، أَخُو فُلَيْحٍ حَدَّثَنَا أَبُو حَازِمٍ، قَالَ كَانَ سَهْلُ بْنُ سَعْدٍ السَّاعِدِيُّ يُقَدِّمُ فِتْيَانَ قَوْمِهِ يُصَلُّونَ بِهِمْ فَقِيلَ لَهُ تَفْعَلُ وَلَكَ مِنَ الْقِدَمِ مَا لَكَ قَالَ إِنِّي سَمِعْتُ رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ يَقُولُ " الإِمَامُ ضَامِنٌ، فَإِنْ أَحْسَنَ، فَلَهُ وَلَهُمْ، وَإِنْ أَسَاءَ - يَعْنِي - فَعَلَيْهِ وَلاَ عَلَيْهِمْ " .
IbnMaja
Establishing the Prayer and the Sunnah Regarding Them • Hadith 981