How can a Muslim avoid showing off (riya') in reciting the Quran and giving the Adhan, while using his beautiful voice to serve the religion, without falling into the whispers of Satan?

A Muslim must intend by his knowledge the Face of Allah and beware of showing off (riyaa'), for Allah accepts no deed except that which is sincerely for His Face and in accordance with what His Messenger brought. A Muslim must not open the door of whisperings (waswasah) to Satan concerning intention or purpose. The duty is to sincerely dedicate one's intention to Allah and to fight the soul from turning to other than Him. Waswasah afflicts everyone who turns to Allah, so the servant must be steadfast, patient, and persistent in remembrance (dhikr) and prayer, for Satan is like a highway robber. Among the best ways to stop waswasah are: completely ignoring it, seeking refuge in Allah, and stopping. One should recite the Qur'an, apply its tajweed (definition), and beautify one's voice with it without affectation or altering its wording.