"...And offer your Salāt (prayer) neither aloud nor in a low voice..." (V.17:110) Sahih al-Bukhari 4723
Arabic hadith text
حَدَّثَنِي طَلْقُ بْنُ غَنَّامٍ، حَدَّثَنَا زَائِدَةُ، عَنْ هِشَامٍ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ قَالَتْأُنْزِلَ ذَلِكَ فِي الدُّعَاءِ.
Translation
Narrated Aisha
The (above) verse was revealed in connection with the invocations.