Musnad Ahmad 31:202

Yahya narrated to us, Hisham and Shu'bah narrated to us, they said: Qatadah narrated to us, from Abu Nadrah, from Abu Sa'id, from the Prophet, peace and blessings of Allah be upon him: "If there are three, let one of them lead them in prayer, and the most entitled of them to the leadership is the one who is most proficient in reciting the Quran."