Sahih Muslim 446
The Book of Prayers
Moderation When Reciting Qur'an In A Prayer When It Is To Be Recited Out Loud, And Making it Neither Too Loud Nor Too Soft, And When There Is The Fear Of Negative Consequences If It Is Recited Out Loud
Ibn 'Abbas reported: The word of (Allah) Great and Glorious: 'And utter not your prayer loudly, nor be low in it" (xvii. 110) was revealed as the Messenger of Allah (may peace beupon him) was hiding himself in Mecca. When he led his Companions in prayer he raised his voice (while reciting the) Qur'an. And when the polytheists heard that, they reviled the Qur'an and Him Who revealed it and him who brought it. Upon this Allah, the Exalted, said to His Messenger (ﷺ): Utter not your prayer so loudly that the polytheists may hear your recitation and (recite it) not so low that it may be inaudible to your Companions. Make them hear the Qur'an, but do not recite it loudly and seek a (middle) way between these. Recite between loud and low tone.