(68) باب فِي صَوْمِ يَوْمٍ وَفِطْرِ يَوْمٍ
'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.
Reference: Sunan Abi Dawud 2448
In-book reference: Book 14, Hadith 136
English translation: Book 13, Hadith 2442