Musnad Abu Ya'la al-Mawsili 110:16

Uthman narrated to us, Husayn bin Isa al-Hanafi narrated to us, al-Hakam bin Aban narrated to us, from Ikrimah, from Ibn Abbas, who said: The Prophet (may Allah bless him and grant him peace) said: "Let the best among you call the adhan, and let your reciters lead you in prayer."