The Messenger of Allah ﷺ said: 'The one who recites the Qur'an loudly is like one who gives charity openly, and the one who recites the Qur'an silently is like the one who gives charity in secret.'" (Using translation from Nasāʾī 1663)   

أَنَّ رَسُولَ اللهِ ﷺ قَالَ «الَّذِي يَجْهَرُ بِالْقُرْآنِ كَالَّذِي يَجْهَرُ بِالصَّدَقَةِ وَالَّذِي يُسِرُّ بِالْقُرْآنِ كَالَّذِي يُسِرُّ بِالصَّدَقَةِ» [147] التَّرْتِيلُ فِي الْقِرَاءَةِ  

"What do you want to know about his prayer (I.e., you can never match it)? He used to pray, then sleep for as long as he had prayed, then he would pray as long as he had slept, then he would sleep as long as he had prayed, until dawn came." Then she described to him his recitation, and she described a clear recitation in which every letter was distinct. (Using translation from Nasāʾī 1629)   

أَنَّهُ سَأَلَ أُمَّ سَلَمَةَ زَوْجَ النَّبِيِّ ﷺ عَنْ قِرَاءَةِ رَسُولِ اللهِ ﷺ وَصَلَاتِهِ قَالَتْ «مَا لَكُمْ وَصَلَاتِهِ كَانَ يُصَلِّي ثُمَّ يَنَامُ قَدْرَ مَا صَلَّى ثُمَّ يُصَلِّي قَدْرَ مَا نَامَ ثُمَّ يَنَامُ بِقَدْرِ مَا صَلَّى حَتَّى يُصْبِحَ ثُمَّ نَعَتَتْ لَهُ قِرَاءَتَهُ فَإِذَا هِيَ تَنْعَتُ قِرَاءَةً مُفَسَّرَةً حَرْفًا حَرْفًا» قَالَ أَبُو عَبْدِ الرَّحْمَنِ يَعْلَى بْنُ مَمْلَكٍ لَيْسَ بِذَاكَ الْمَشْهُورِ  

"I never saw the Messenger of Allah ﷺ offer his voluntary prayers sitting down until one year before his death. Then he used to pray sitting down, reciting the surah so slowly that it seemed to be longer than a surah that is longer." (Using translation from Nasāʾī 1658)  

مَا رَأَيْتُ رَسُولَ اللهِ ﷺ صَلَّى فِي سُبْحَتَهُ قَاعِدًا قَطُّ حَتَّى كَانَ قَبْلَ وَفَاتِهِ بِعَامٍ فَكَانَ «يُصَلِّي قَاعِدًا وَيُقْرَأُ بِالسُّورَةِ فَيُرَتِّلُهَا حَتَّى تَكُونَ أَطْوَلَ مِنْ أَطْوَلِ مِنْهَا»