Sunan an-Nasa'i, Volume 3, Book 22, Hadith 2346 (DarusSalam) ⓘ
Abdullah bin 'Amr bin Al-As said: "The Messenger of Allah said: 'The most beloved fasting to Allah, the mighty and sublime, is the fast of Dawud, peace be upon him. He used to fast one day and not the next. And the most beloved prayer to Allah, the mighty and sublime, is the prayer of Dawud, peace be upon him. He used to sleep half the night, stand for one-third of it (in prayer), and sleep for one-sixth of it."'
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ عَمْرِو بْنِ دِينَارٍ، عَنْ عَمْرِو بْنِ أَوْسٍ، أَنَّهُ سَمِعَ عَبْدَ اللَّهِ بْنَ عَمْرِو بْنِ الْعَاصِ، يَقُولُ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " أَحَبُّ الصِّيَامِ إِلَى اللَّهِ عَزَّ وَجَلَّ صِيَامُ دَاوُدَ عَلَيْهِ السَّلاَمُ كَانَ يَصُومُ يَوْمًا وَيُفْطِرُ يَوْمًا وَأَحَبُّ الصَّلاَةِ إِلَى اللَّهِ عَزَّ وَجَلَّ صَلاَةُ دَاوُدَ عَلَيْهِ السَّلاَمُ كَانَ يَنَامُ نِصْفَ اللَّيْلِ وَيَقُومُ ثُلُثَهُ وَيَنَامُ سُدُسَهُ " .
also referenced under: Hadith 2344 (Reference) & Book 22, Hadith 255 (In-Book)