Musnad Ahmad 31:464

Shuja' ibn al-Walid narrated to us, from Sa'id ibn Abi 'Aruba, from Qatadah, from Abu Nadrah, from Abu Sa'id al-Khudri, that the Prophet of Allah, peace and blessings of Allah be upon him, said: "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 recitation."