Thumamah bin Shufayy (Abu Ali al-Hamdani) said: We were with Sayyiduna Uqbah bin Amir al-Juhani (may Allah be pleased with him) when the time of prayer came, so we asked him to lead us in prayer, but he refused and said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Whenever a servant leads a people in prayer, he also takes on the responsibility for their prayer. If he performs it well, the reward is for both him and them; and if he falls short, the burden is upon him alone and not upon them."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14979