Hadith: The best (voluntary) fast in the sight of Allah is the fast of Dawūd, and the best (voluntary) prayer in the sight of Allah is the prayer of Dawūd. He used to sleep half of the night, stand to pray one third of it, and then sleep one sixth of it, and he used to fast every other day

عن عبد الله بن عمرو بن العاص رضي الله عنهما قال: قال رسول الله صلى الله عليه وسلم : «إن أَحَبَّ الصيام إلى الله صِيَامُ داود، وأحب الصلاة إلى الله صلاة داود، كان يَنَامُ نِصْفَ اللَّيْلِ، وَيَقُومُ ثُلُثَهُ، وَيَنَامُ سُدُسَهُ، وكان يصوم يومًا ويُفطِرُ يومًا».
[صحيح] - [متفق عليه]

‘Abdullāh ibn ‘Amr ibn al-‘Ās (may Allah be pleased with him) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) said: "The best (voluntary) fast in the sight of Allah is the fast of Dawūd, and the best (voluntary) prayer in the sight of Allah is the prayer of Dawūd. He used to sleep half of the night, stand to pray one third of it, and then sleep one sixth of it, and he used to fast every other day."
[Authentic hadith] - [Narrated by Bukhari & Muslim]

Explanation

‘Abdullāh ibn ‘Amr (may Allah be pleased with him) informs us in this Hadīth that the Prophet (may Allah's peace and blessings be upon him) said that the best fast and night prayer in the sight of Allah, the Almighty, are those of His Prophet Dawūd (peace be upon him). He used to fast one day and not fast on the next day, as this manner of fasting fulfills worship and gives the body its share of rest at the same time. He used to sleep the first half of the night to wake up feeling active enough to perform worship. He would then pray one third of the night then sleep its last sixth to be active for the acts of worship that were to be performed in the early morning. This is the way that the Prophet (may Allah's peace and blessings be upon him) encouraged Muslims to follow.