Musnad Ahmad 32:722

'Abd al-Razzaq narrated to us, Ibn Jurayj informed us, he said: 'Abd al-Malik said to me that Anas ibn Malik said: From the Prophet, peace and blessings of Allah be upon him, he said: "The one who leads the people in prayer is the one among them who is most proficient in the recitation of the Quran."