question #2 Sahih al-Bukhari 774, Book 10, Hadith 168 : How does the Prophet’s practice of reciting aloud or quietly in prayers guide Muslims in their own prayer practices?

The Prophet (ﷺ) recited aloud in the prayers in which he was ordered to do so and quietly in the prayers in
which he was ordered to do so. “And your Lord is not forgetful.” “Verily there was a good example
for you in the ways of the Prophet.”