Musannaf Ibn Abi Shayba 2:258

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from ‘Umar bin Sa’d bin Abi Husayn al-Makki, that a mu’adhdhin (caller to prayer) gave the adhan and used tarab (melodic modulation/singing style) in his adhan. ‘Umar bin ‘Abd al-‘Aziz said to him: "Give the adhan in a simple/easy manner, or else withdraw from us."