Musnad Ahmad 435:34

Ibn Numayr and Ya‘la narrated to us, they said: Talha—meaning Ibn Yahya—narrated to us, from ‘Isa ibn Talha, he said: I heard Mu‘awiyah saying: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "Indeed, the callers to prayer (mu'adhdhins) will have the longest necks of all people on the Day of Resurrection."