It is narrated from Al-Bayadi (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) came to the people while they were praying. The people's voices were raised due to their recitation, so he (peace and blessings be upon him) said: "The one who is praying is whispering to his Lord, so he should see what he whispers, and do not recite the Qur'an aloud over one another."