It was narrated that 'Abdullah bin 'Amr said:

"My father got me married to a woman and he came to visit her and said: 'What do you think of your husband?' She said: 'What a wonderful man he is. He does not sleep at night and he does not break his fast during the day.' He got upset with me and said: 'I got you married to a woman from among the Muslims and you have neglected her.' I did not pay attention to what he said because of my energy and love of worship. News of that reached the Prophet and he said: 'But I stand (in prayer) and I sleep, I fast and I break my fast. So stand (in prayer) and sleep, fast and break your fast.' He said: 'Fast three days of every month.' I said: 'I am able to do more than that.' He said: 'O bserve the fast of Dawud, peace be upon him: fast one day and break your fast one day.' I said: 'I am able to do more than that.' He said: 'Read the Quran (once) every month.' Then it ended up being every fifteen days, and I still said: 'I am able to do more than that."' 'Ata said: "someone who heard him told me that Ibn 'Umar (said) that the Prophet ﷺ said: 'Whoever fasts every day of his life, then he has not fasted."

أَخْبَرَنَا أَبُو حَصِينٍ عَبْدُ اللَّهِ بْنُ أَحْمَدَ بْنِ عَبْدِ اللَّهِ بْنِ يُونُسَ، قَالَ حَدَّثَنَا عَبْثَرٌ، قَالَ حَدَّثَنَا حُصَيْنٌ، عَنْ مُجَاهِدٍ، عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو، قَالَ زَوَّجَنِي أَبِي امْرَأَةً فَجَاءَ يَزُورُهَا فَقَالَ كَيْفَ تَرَيْنَ بَعْلَكِ فَقَالَتْ نِعْمَ الرَّجُلُ مِنْ رَجُلٍ لاَ يَنَامُ اللَّيْلَ وَلاَ يُفْطِرُ النَّهَارَ . فَوَقَعَ بِي وَقَالَ زَوَّجْتُكَ امْرَأَةً مِنَ الْمُسْلِمِينَ فَعَضَلْتَهَا . قَالَ فَجَعَلْتُ لاَ أَلْتَفِتُ إِلَى قَوْلِهِ مِمَّا أَرَى عِنْدِي مِنَ الْقُوَّةِ وَالاِجْتِهَادِ فَبَلَغَ ذَلِكَ النَّبِيَّ ﷺ فَقَالَ " لَكِنِّي أَنَا أَقُومُ وَأَنَامُ وَأَصُومُ وَأُفْطِرُ فَقُمْ وَنَمْ وَصُمْ وَأَفْطِرْ " . قَالَ " صُمْ مِنْ كُلِّ شَهْرٍ ثَلاَثَةَ أَيَّامٍ " . فَقُلْتُ أَنَا أَقْوَى مِنْ ذَلِكَ . قَالَ " صُمْ صَوْمَ دَاوُدَ عَلَيْهِ السَّلاَمُ صُمْ يَوْمًا وَأَفْطِرْ يَوْمًا " . قُلْتُ أَنَا أَقْوَى مِنْ ذَلِكَ . قَالَ " اقْرَإِ الْقُرْآنَ فِي كُلِّ شَهْرٍ " . ثُمَّ انْتَهَى إِلَى خَمْسَ عَشْرَةَ وَأَنَا أَقُولُ أَنَا أَقْوَى مِنْ ذَلِكَ .