regarding the explanation of the Verse:-- '(O Muhammad!) Neither say your prayer aloud, nor say it in a low tone.' (17.110) This Verse was revealed while Messenger of Allah ﷺ was hiding himself at Mecca. At that time, when he led his companions in prayer, he used to raise his voice while reciting the Qur'an; and if the pagans heard him, they would abuse the Qur'an, its Revealer, and the one who brought it. So Allah said to His Prophet: "Neither say your prayer aloud. i.e., your recitation (of Qur'an) lest the pagans should hear (it) and abuse the Qur'an" nor say it in a low tone, "lest your voice should fail to reach your companions, "but follow a way between." (17.110)  

فِي قَوْلِهِ تَعَالَى {وَلاَ تَجْهَرْ بِصَلاَتِكَ وَلاَ تُخَافِتْ بِهَا} قَالَ نَزَلَتْ وَرَسُولُ اللَّهِ ﷺ مُخْتَفٍ بِمَكَّةَ فَكَانَ إِذَا صَلَّى بِأَصْحَابِهِ رَفَعَ صَوْتَهُ بِالْقُرْآنِ فَإِذَا سَمِعَهُ الْمُشْرِكُونَ سَبُّوا الْقُرْآنَ وَمَنْ أَنْزَلَهُ وَمَنْ جَاءَ بِهِ فَقَالَ اللَّهُ لِنَبِيِّهِ ﷺ {وَلاَ تَجْهَرْ بِصَلاَتِكَ} أَىْ بِقِرَاءَتِكَ فَيَسْمَعَ الْمُشْرِكُونَ فَيَسُبُّوا الْقُرْآنَ {وَلاَ تُخَافِتْ بِهَا} عَنْ أَصْحَابِكَ فَلاَ تُسْمِعُهُمْ {وَابْتَغِ بَيْنَ ذَلِكَ سَبِيلاً}  

The Verse:-- '(O Muhammad!) Neither say your prayer aloud nor say it in a low tone.' (17.110) was revealed in connection with the invocations.  

نَزَلَتْ هَذِهِ الآيَةُ {وَلاَ تَجْهَرْ بِصَلاَتِكَ وَلاَ تُخَافِتْ بِهَا} فِي الدُّعَاءِ  

Abu Huraira said, "Messenger of Allah ﷺ 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."  

قَالَ رَسُولُ اللَّهِ ﷺ لَيْسَ مِنَّا مَنْ لَمْ يَتَغَنَّ بِالْقُرْآنِ وَزَادَ غَيْرُهُ يَجْهَرُ بِهِ