Musnad Ahmad 482:134

Abdullah ibn al-Harith narrated to us, al-Aslami narrated to me, Abu Ali al-Hamdani narrated to me, from Uqbah ibn Amir, who said: We went out with Uqbah ibn Amir on a journey we were taking, and the time for prayer arrived. We asked him to lead us in prayer, but he refused us and said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: "No servant leads a people in prayer except that he takes responsibility for what is upon them in their prayer. If he does well, it is for him, and if he does poorly, it is against him."