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  

" And utter not thy prayer loudly, not be low in it" (xvii. 110) relate to supplication (du'a').  

عَنْ عَائِشَةَ فِي قَوْلِهِ ﷻ { وَلاَ تَجْهَرْ بِصَلاَتِكَ وَلاَ تُخَافِتْ بِهَا} قَالَتْ أُنْزِلَ هَذَا فِي الدُّعَاءِ  

[Machine] This verse is recited in the tashahhud: "And do not be loud in your prayer or too low - and seek between that a way." [Al Isra 110]  

نَزَلَتْ هَذِهِ الْآيَةُ فِي التَّشَهُّدِ {وَلَا تَجْهَرْ بِصَلَاتِكَ وَلَا تُخَافِتْ بِهَا} [الإسراء 110]  

The Verse: 'Neither say your prayer aloud, nor say it in a low tone.' (17.110) was revealed as regards invocation. (Using translation from Bukhārī 6327)   

عَنْ عَائِشَةَ فِي قَوْلِهِ جَلَّ وَعَزَّ {وَلَا تَجْهَرْ بِصَلَاتِكَ وَلَا تُخَافِتْ بِهَا} [الإسراء 110] نَزَلَتْ فِي الدُّعَاءِ  

[Machine] In His saying, "Do not raise your voice in prayer nor be silent in it," [Surah Al-Isra 110], it means supplication.  

ؓ فِي قَوْلِهِ {لَا تَجْهَرْ بِصَلَاتِكَ وَلَا تُخَافِتْ بِهَا} [الإسراء 110] قَالَتْ هُوَ الدُّعَاءُ