Musnad Ahmad 31:308

Muhammad ibn Ja‘far narrated to us—and he was asked about three people who gather and the prayer time arrives—he said: Sa‘id narrated to us, from Qatadah, from Abu Nadrah, from Abu Sa‘id al-Khudri, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "If three gather, then 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."