Sahih Bukhari
Oneness, Uniqueness of Allah (Tawheed)
Volume: 009 / Book Number: 093 / Hadith Number: 618
Narrated Abu Salama:
Abu Huraira said, "Allah's Apostle said, 'Whoever does not recite Qur'an in a nice voice is not from us,' and others said extra," (that means) to recite it aloud."