[Machine] The Messenger of Allah ﷺ said, "The most beloved prayer to Allah the Exalted is the prayer of Dawud (David). He would sleep for half the night, then stand in prayer for one-third of it, and then sleep for the remainder. The most beloved fast to Allah the Exalted is the fast of Dawud. He would fast one day and break his fast the next day."  

قَالَ رَسُولُ اللهِ ﷺ أَحَبُّ الصَّلَاةِ إِلَى اللهِ تَعَالَى صَلَاةُ دَاوُدَ كَانَ يَرْقُدُ شَطْرَ اللَّيْلِ ثُمَّ يَقُومُ ثُلُثَهُ بَعْدَ شَطْرِهِ ثُمَّ يَرْقُدُ آخِرَهُ وَأَحَبُّ الصِّيَامِ إِلَى اللهِ تَعَالَى صِيَامُ دَاوُدَ كَانَ يَصُومُ يَوْمًا وَيُفْطِرُ يَوْمًا  

Observe fast for a day and there would be reward for you for the rest (of the days). He said: I am capable of doing more than this. He then said: Observe fast for two days, and there would be reward for you for the rest (of the days). He said: I am capable of doing more than this. He (the Holy Prophet) said: Observe fast for three days and there would be reward for you for the rest of the days. He said: I am capable of doing more than this, whereupon he said: Observe fast for four days and there would be reward for you for the rest of the days. He said: I am capable of doing more than this. Thereupon he said: Then observe fast (which is the) best in the eye of Allah, the fast of David (peace be upon him) ; he used to observe fast one day and break on the other day. (Using translation from Muslim 1159n)   

أَنَّ رَسُولَ اللهِ ﷺ قَالَ صُمْ يَوْمًا وَلَكَ أَجْرُ مَا بَقِيَ قَالَ إِنِّي أُطِيقُ أَكْثَرَ مِنْ ذَلِكَ قَالَ صُمْ يَوْمَيْنِ وَلَكَ أَجْرُ مَا بَقِيَ قَالَ إِنِّي أُطِيقُ أَكْثَرَ مِنْ ذَلِكَ قَالَ صُمْ ثَلَاثَةَ أَيَّامٍ وَلَكَ أَجْرُ مَا بَقِيَ قَالَ إِنِّي أُطِيقُ أَكْثَرَ مِنْ ذَلِكَ قَالَ صُمْ أَرْبَعَةَ أَيَّامٍ وَلَكَ أَجْرُ مَا بَقِيَ قَالَ إِنِّي أُطِيقُ أَكْثَرَ مِنْ ذَلِكَ قَالَ صُمْ أَفْضَلَ الصِّيَامِ عِنْدَ اللهِ صَوْمَ دَاوُدَ كَانَ يَصُومُ يَوْمًا وَيُفْطِرُ يَوْمًا