'Abd Allah b. 'And (b. al-'As) said:The Messenger of Allah (ﷺ) said to me: The fast most liked by Allah is the one observed by Dawud (David), and the prayer dearer to Allah is the one offered by Dawud (David): he would sleep half the night, and stand (in prayer) one-third of it, and sleep one-sixth of it. He would go without fasting one day, and fast the other day.
حَدَّثَنَا أَحْمَدُ بْنُ حَنْبَلٍ، وَمُحَمَّدُ بْنُ عِيسَى، وَمُسَدَّدٌ، - وَالإِخْبَارُ فِي حَدِيثِ أَحْمَدَ - قَالُوا حَدَّثَنَا سُفْيَانُ قَالَ سَمِعْتُ عَمْرًا قَالَ أَخْبَرَنِي عَمْرُو بْنُ أَوْسٍ سَمِعَهُ مِنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو قَالَ قَالَ لِي رَسُولُ اللَّهِ صلى الله عليه وسلم " أَحَبُّ الصِّيَامِ إِلَى اللَّهِ تَعَالَى صِيَامُ دَاوُدَ وَأَحَبُّ الصَّلاَةِ إِلَى اللَّهِ صَلاَةُ دَاوُدَ كَانَ يَنَامُ نِصْفَهُ وَيَقُومُ ثُلُثَهُ وَيَنَامُ سُدُسَهُ وَكَانَ يُفْطِرُ يَوْمًا وَيَصُومُ يَوْمًا " .
AbuDaud
Fasting (Kitab Al-Siyam) • Hadith 2448