´It was narrated that 'Uthman bin Abul-As said:` "The last instruction that the Messenger of Allah gave to me was that I should not appoint a Mu'adh-dhin who took payment for the Adhan." (sahih)
Hadith ReferenceSunan Ibn Majah / The Book of the Adhan and the Sunnah Regarding It / Hadith: 714