He then said to the youth, “My nephew, what do you do when you pray?”
The young man answered, “I recite Sūrat al-Fātiḥah, ask Allah for Paradise, and seek His protection from the Fire. As for your murmuring and Muʿādh’s murmuring, I do not understand any of it.”
The Messenger of Allah ﷺ replied, “Muʿādh and I circle around these two requests—or something to that effect.”
The youth added, “But Muʿādh will find out when the people return and are told that the enemy has arrived.”
When the army came back, the young man had been martyred. Later the Messenger of Allah ﷺ said to Muʿādh, “What became of my adversary and yours?”
Muʿādh replied, “Messenger of Allah, Allah spoke the truth and I was mistaken—he was martyred.” (p. 411–412)

Reciting Aloud and Silently in the Five Daily Prayers and Other Prayers
He ﷺ used to recite aloud in the dawn prayer (Ṣubḥ) and in the first two rakʿahs of Maghrib and ʿIshāʾ, while he recited quietly in Ẓuhr and ʿAṣr and in the third rakʿah of Maghrib and the last two rakʿahs of ʿIshāʾ. They could tell that he was reciting, even when he did so quietly, by the movement of his beard, and sometimes he would let them hear a verse. He also recited aloud in the Friday prayer, the two ʿĪd prayers, the rain-seeking prayer (istiskāʾ), and the eclipse prayer. (p. 413–418)

Reciting Aloud and Silently in the Night Prayer
As for the night prayer, at times he recited quietly and at times aloud. When he recited in his house, those who were in the room could hear him—an indication of a middle course between loud and silent recitation—and occasionally he raised his voice further so that someone standing outside his chamber could hear.
He instructed Abū Bakr and ʿUmar to do the same. One night he went out and found Abū Bakr praying in a low voice, then passed by ʿUmar ibn al-Khaṭṭāb, who was praying in a raised voice. When they gathered before the Prophet ﷺ, he said, “Abū Bakr, I passed by you while you were praying in a low voice?” He replied, “I made sure the One I was addressing could hear me, Messenger of Allah.” He then said to ʿUmar, “I passed by you while you were praying in a loud voice?” He answered, “Messenger of Allah, I was waking the drowsy and driving Satan away.” The Prophet ﷺ therefore said, “Abū Bakr, raise your voice a little,” and to ʿUmar, “Lower your voice a little.”
He used to say, “The one who recites the Quran aloud is like someone who gives charity openly, whereas the one who recites it quietly is like someone who gives charity in secret.” (p. 419–428)