Musnad Abu Ya'la al-Mawsili 107:28

Abu Khaythama narrated to us, Hibban narrated to us, Zuhayr narrated to us, Abd al-Rahman ibn Harmala narrated to us, that a man from Alexandria, from Hamdan, told him, who was called Abu Ali, he said: We went out on a journey and Uqba ibn Amir was with us. We said to him: "Lead us in prayer, may Allah have mercy on you." He said: "I will not do it. I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: 'Whoever leads the people in prayer, and he hits the time and completes the prayer, then it is for him and for them. And whoever falls short of that in anything, then it is upon him and not upon them.'"