Sahih Bukhari Volume 9, Book 97, Hadith 7492

حَدَّثَنَا مُسَدَّدٌ، عَنْ هُشَيْمٍ، عَنْ أَبِي بِشْرٍ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ ‏{‏وَلاَ تَجْهَرْ بِصَلاَتِكَ وَلاَ تُخَافِتْ بِهَا‏}‏ قَالَ أُنْزِلَتْ وَرَسُولُ اللَّهِ صلى الله عليه وسلم مُتَوَارٍ بِمَكَّةَ، فَكَانَ إِذَا رَفَعَ صَوْتَهُ سَمِعَ الْمُشْرِكُونَ فَسَبُّوا الْقُرْآنَ وَمَنْ أَنْزَلَهُ وَمَنْ جَاءَ بِهِ‏.‏ وَقَالَ اللَّهُ تَعَالَى ‏{‏وَلاَ تَجْهَرْ بِصَلاَتِكَ وَلاَ تُخَافِتْ بِهَا‏}‏ لاَ تَجْهَرْ بِصَلاَتِكَ حَتَّى يَسْمَعَ الْمُشْرِكُونَ، وَلاَ تُخَافِتْ بِهَا عَنْ أَصْحَابِكَ فَلاَ تُسْمِعُهُمْ ‏{‏وَابْتَغِ بَيْنَ ذَلِكَ سَبِيلاً‏}‏ أَسْمِعْهُمْ وَلاَ تَجْهَرْ حَتَّى يَأْخُذُوا عَنْكَ الْقُرْآنَ‏

Narrated By Ibn 'Abbas : (Regarding the Verse): 'Neither say your prayer aloud, nor say it in a low tone.' (17.110) This Verse was revealed while Allah's Apostle was hiding himself in Mecca, and when he raised his voice while reciting the Qur'an, the pagans would hear him and abuse the Qur'an and its Revealer and to the one who brought it. So Allah said: 'Neither say your prayer aloud, nor say it in a low tone.' (17.110) That is, 'Do not say your prayer so loudly that the pagans can hear you, nor say it in such a low tone that your companions do not hear you.' But seek a middle course between those (extremes), i.e. let your companions hear, but do not relate the Qur'an loudly, so that they may learn it from you.