"The Messenger of Allah said to me: 'Read the Qur'an in a month.' I said: 'I am able to do more than that. ' And I kept asking him until he said: 'In five days.' And he said: 'Fast three days a month.' I said: 'I am able to do more than that.' And 'Observe thhe most beloved of fasting to Allah, the Mighty and Sublime, the fast one day and not the next." (Suahih). (Using translation from Nasāʾī 2400)
لِي رَسُولُ اللهِ ﷺ اقْرَأِ الْقُرْآنَ فِي شَهْرٍ فَقُلْتُ إِنِّي أُطِيقُ أَكْثَرَ مِنْ ذَلِكَ فَلَمْ أَزَلْ أَطْلُبُ إِلَيْهِ حَتَّى قَالَ اقْرَإِ الْقُرْآنَ فِي خَمْسَةِ أَيَّامٍ وَصُمْ ثَلَاثَةَ أَيَّامٍ مِنَ الشَّهْرِ قُلْتُ إِنِّي أُطِيقُ أَكْثَرَ مِنْ ذَلِكَ قَالَ فَصُمْ أَحَبَّ الصَّوْمِ إِلَى اللهِ ﷻ صَوْمِ دَاوُدَ عَلَيْهِ السَّلَامُ كَانَيَصُومُ يَوْمًا وَيُفْطِرُ يَوْمًا