7:55Al-A'raaf

When one of you makes a supplication (to his Lord) one should not say: O Allah, grant me pardon, if Thou so likest, but one should beg one's (Lord) with a will and full devotion, for there is nothing so great in the eye of Allah which He cannot grant.

The nearest a servant come to his Lord is when he is prostrating himself, so make supplication often.

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

The word of (Allah) Great and Glorious: 'And utter not thy prayer loudly, nor be low in it" (xvii. 110) was revealed as the Messenger of Allah (may peace beupon him) was hiding himself in Mecca. When he led his Companions in prayer he raised his voice (while reciting the) Qur'an. And when the polytheists heard that, they reviled the Qur'an and Him Who revealed it and him who brought it. Upon this Allah, the Exalted, said to His Apostle (ﷺ): Utter not thy prayer so loudly that the polytheists may hear thy recitation and (recite it) not so low that it may be inaudible to your Companions. Make them hear the Qur'an, but do not recite it loudly and seek a (middle) way between these. Recite between loud and low tone.

(regarding): 'Neither say your, prayer aloud, nor say it in a low tone.' (17.110) This Verse was revealed while Allah's Messenger (ﷺ) was hiding himself in Mecca. When he prayed with his companions, he used to raise his voice with the recitation of Qur'an, and if the pagans happened to hear him, they would abuse the Qur'an, the One who revealed it and the one who brought it. Therefore Allah said to His Prophet : 'Neither say your prayer aloud.' (17.110) i.e. do not recite aloud lest the pagans should hear you, but follow a way between.