Al-Barā' ibn ‘Āzib (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said: "Adorn the Qur'an with your voices."
The Hadīth means that one should adorn the Qur'an by beautifying the voice when reciting it, as the good words increase their goodness and excellence when communicated in a beautiful voice. The wisdom behind this is to encourage extra contemplation of the meanings of the Qur‘an and a deeper understanding of the commandments, prohibitions, warnings, and glad tidings included in the recited verses. People naturally incline to a beautiful voice and the mind can be cleared of all distracting thoughts by virtue it, and in turn it draws the full attention to listening to and reflecting on the Qur'an. As a result, the main purpose of humility and submission would be achieved. Beautifying the voice, as mentioned in the Hadīth, refers to a beautiful recitation that brings humility, not to tainting the recitation with melodious music that violates the limits of recitation.