Sunan an-Nasa'i, Volume 2, Book 20, Hadith 1630 (DarusSalam) ⓘ

It was narrated from Ya'la bin Mamlak that he asked Umm Salamah, the wife of the Prophet about the recitation and prayer of the Messenger of Allah. She said: "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.

أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا اللَّيْثُ، عَنْ عَبْدِ اللَّهِ بْنِ عُبَيْدِ اللَّهِ بْنِ أَبِي مُلَيْكَةَ، عَنْ يَعْلَى بْنِ مَمْلَكٍ، أَنَّهُ سَأَلَ أُمَّ سَلَمَةَ زَوْجَ النَّبِيِّ صلى الله عليه وسلم عَنْ قِرَاءَةِ رَسُولِ اللَّهِ صلى الله عليه وسلم وَعَنْ صَلاَتِهِ فَقَالَتْ مَا لَكُمْ وَصَلاَتَهُ كَانَ يُصَلِّي ثُمَّ يَنَامُ قَدْرَ مَا صَلَّى ثُمَّ يُصَلِّي قَدْرَ مَا نَامَ ثُمَّ يَنَامُ قَدْرَ مَا صَلَّى حَتَّى يُصْبِحَ ‏.‏ ثُمَّ نَعَتَتْ لَهُ قِرَاءَتَهُ فَإِذَا هِيَ تَنْعَتُ قِرَاءَةً مُفَسَّرَةً حَرْفًا حَرْفًا ‏.‏