Messenger of Allah ﷺ entered upon me and said, "Have I not been informed that you offer prayer all the night and fast the whole day?" I said, "Yes." He said, "Do not do so; Offer prayer at night and also sleep; Fast for a few days and give up fasting for a few days because your body has a right on you, and your eye has a right on you, and your guest has a right on you, and your wife has a right on you. I hope that you will have a long life, and it is sufficient for you to fast for three days a month as the reward of a good deed, is multiplied ten times, that means, as if you fasted the whole year." I insisted (on fasting more) so I was given a hard instruction. I said, "I can do more than that (fasting)" The Prophet said, "Fast three days every week." But as I insisted (on fasting more) so I was burdened. I said, "I can fast more than that." The Prophet ﷺ said, "Fast as Allah's prophet David used to fast." I said, "How was the fasting of the prophet David?" The Prophet ﷺ said, "One half of a year (i.e. he used to fast on alternate days). ' (Using translation from Bukhārī 6134)   

قَالَ رَسُولُ اللهِ ﷺ «أَلَمْ أُخْبَرْ أَنَّكَ تَصُومُ النَّهَارَ وَتَقُومُ اللَّيْلَ؟» قُلْتُ نَعَمْ يَا رَسُولَ اللهِ قَالَ «فَلَا تَفْعَلْ صُمْ وَأَفْطِرْ وَنَمْ وَقُمْ فَإِنَّ لِنَفْسِكَ عَلَيْكَ حَقًّا وَلِجَسَدِكَ عَلَيْكَ حَقًّا وَإِنَّ لِزَوْجَتِكَ عَلَيْكَ حَقًّا وَإِنَّ بِحَسْبِكَ أَنْ تَصُومَ ثَلَاثَةَ أَيَّامٍ مِنْ كُلِّ شَهْرٍ فَإِنَّ الْحَسَنَةَ بِعَشْرِ أَمْثَالِهَا فَإِذَا ذَلِكَ صِيَامُ الدَّهْرِ كُلِّهِ» فَشَدَّدْتُ فَشُدِّدَ عَلَيَّ قُلْتُ يَا رَسُولَ اللهِ إِنِّي أَجِدُ قُوَّةً قَالَ «فَصُمْ مِنْ كُلِّ جُمُعَةٍ ثَلَاثَةَ أَيَّامٍ» فَشَدَّدْتُ فَشُدِّدَ عَلَيَّ قُلْتُ يَا رَسُولَ اللهِ إِنِّي أَجِدُ قُوَّةً قَالَ «فَصُمْ صِيَامَ نَبِيِّ اللهِ دَاوُدَ وَلَا تَزِدْ عَلَيْهِ» قُلْتُ يَا رَسُولَ اللهِ وَمَا صِيَامُ دَاوُدَ قَالَ «صِيَامُ نِصْفِ الدَّهْرِ»