Sahih Al Bukhari Hadith Number 772

Narrated Abu Huraira: The Qur’an is recited in every prayer and in those prayers in which Allah’s Messenger (peace be upon him) recited aloud for us, we recite aloud in the same prayers for you; and the prayers in which the Prophet (peace be upon him) recited quietly, we recite quietly. If you recite “Al-Fatiha” only it is sufficient but if you recite something else in addition, it is better.

10  Call to Prayers (Adhaan)
Hadith number 772
Volume no 1
Chapter: 104 (The recitation of the Qur’an in the Fajr prayer)