"The Prophet ﷺ used to raise his voice when reciting Quran, and when the idolaters heard his voice they would insult the Quran and the one who had brought it. So the Prophet ﷺ began to lower his voice such that his companions would not hear him. Then Allah (SWT), the Mighty and Sublime, revealed: 'And offer your salah (prayer) neither aloud nor in a low voice, but follow a way between.'" (Using translation from Nasāʾī 1012)
كَانَ النَّبِيُّ ﷺ يَرْفَعُ صَوْتَهُ بِالْقُرْآنِ وَكَانَ الْمُشْرِكُونَ إِذَا سَمِعُوا صَوْتَهُ سَبُّوا الْقُرْآنَ وَمَنْ جَاءَ بِهِ فَكَانَ النَّبِيُّ ﷺ يَخْفِضُ صَوْتَهُ بِالْقُرْآنِ مَا كَانَ يَسْمَعُهُ أَصْحَابَهُ فَأَنْزَلَ اللهُ {وَلَا تَجْهَرْ بِصَلَاتِكَ وَلَا تُخَافِتْ} [الإسراء 110] بِهَا وَابْتَغِ بَيْنَ ذَلِكَ سَبِيلًا