Sahih Bukhari
Characteristics of Prayer
Volume: 001 / Book Number: 012 / Hadith Number: 741
Narrated Ibn 'Abbas:
The Prophet recited aloud in the prayers in which he was ordered to do so and quietly in the prayers in which he was ordered to do so. "And your Lord is not forgetful." "Verily there was a good example for you in the ways of the Prophet."