Sahih Bukhari
Call to Prayers (Adhaan)
Volume: 001 / Book Number: 011 / Hadith Number: 663
Narrated Abu Huraira:
Allah's Apostle said, "If the Imam leads the prayer correctly then he and you will receive the rewards but if he makes a mistake (in the prayer) then you will receive the reward for the prayer and the sin will be his."