'It was said to the Prophet that a man fasted for the rest of his life. He said: 'I wish that he had never eaten.' They said: 'Two-thirds (of a lifetime)?' He said: 'That is too much.' Then he said: 'Shall I not tell you of that which will take away impurity from the heart? Fasting three days each month." 'Ata said: "someone who heard him told me that Ibn 'Umar (said) that the Prophet said: 'Whoever fasts every day of his life, then he has not fasted." (Using translation from Nasāʾī 2385)  

عَنْ رَجُلٍ مِنْ أَصْحَابِ النَّبِيِّ ﷺ قَالَ قِيلَ لِلنَّبِيِّ ﷺ رَجُلٌ يَصُومُ الدَّهْرَ قَالَ «وَدِدْتُ أَنَّهُ لَمْ يَطْعَمِ الدَّهْرَ» قَالُوا فَثُلُثَيْهِ؟ قَالَ «أَكْثَرَ» قَالُوا فَنِصْفُهُ؟ قَالَ «أَكْثَرَ» ثُمَّ قَالَ «أَلَا أُخْبِرُكُمْ بِمَا يُذْهِبُ وَحَرَ الصَّدْرِ؟ صَوْمُ ثَلَاثَةِ أَيَّامٍ مِنْ كُلِّ شَهْرٍ»  

"A man came to the Messenger of Allah and said: 'O Messenger of Allah, what do you say about a man who fated for the rest of his life?' The Messenger of Allah said: 'I wish that he would never eat for the rest of his life.' He said: 'Two-thirds ( of a lifetime)?' he said: 'That is too much.' He said: 'Half?' He said: 'Shall I not tell you of that which will take away impurity from the heart?' He said: 'Yes.' He said: 'Fasting for three days each month."' 'Ata said: "someone who heard him told me that Ibn 'Umar (said) that the Prophet said: 'Whoever fasts every day of his life, then he has not fasted." (Using translation from Nasāʾī 2386)  

أَتَى رَسُولَ اللهِ ﷺ رَجُلٌ فَقَالَ يَا رَسُولَ اللهِ مَا تَقُولُ فِي رَجُلٍ صَامَ الدَّهْرَ؟ فَقَالَ رَسُولُ اللهِ ﷺ «وَدِدْتُ أَنَّهُ لَمْ يَطْعَمِ الدَّهْرَ شَيْئًا» قَالَ فَثُلُثَيْهِ؟ قَالَ «أَكْثَرَ» قَالَ فَنِصْفَهُ قَالَ «أَكْثَرَ أَلَا أُخْبِرُكُمْ بِمَا يُذْهِبُ وَحَرَ الصَّدْرِ؟» قَالُوا بَلَى قَالَ «صَوْمُ ثَلَاثَةِ أَيَّامٍ مِنْ كُلِّ شَهْرٍ»  

"Umar said: 'O Messenger of Allah, what about a person who fasted for an entire lifetime?' He said: 'He neither fasted nor broke his fast for one day?' He said: 'Can anyone do that?' He said: 'What about a person who fasted for one day?' He said: 'That is the fast of Dawud, peace be upon him.' He said: 'What about a person who fasted for one day, and broke his fast for two days?' he said: 'I wish that I could do that.' Then he said: 'Three days of each month, and from Ramadan to Ramadan, this is fasting for an entire lifetime."' 'Ata said: "someone who heard him told me that Ibn 'Umar (said) that the Prophet said: 'Whoever fasts every day of his life, then he has not fasted." (Using translation from Nasāʾī 2387)  

قَالَ عُمَرُ يَا رَسُولَ اللهِ كَيْفَ بِمَنْ يَصُومُ الدَّهْرَ كُلَّهُ؟ قَالَ «لَا صَامَ وَلَا أَفْطَرَ أَوْ لَمْ يَصُمْ وَلَمْ يُفْطِرْ» قَالَ يَا رَسُولَ اللهِ كَيْفَ بِمَنْ يَصُومُ يَوْمَيْنِ وَيُفْطِرُ يَوْمًا؟ قَالَ «وَيُطِيقُ ذَلِكَ أَحَدٌ؟» قَالَ فَكَيْفَ بِمَنْ يَصُومُ يَوْمًا وَيُفْطِرُ يَوْمًا؟ قَالَ «ذَاكَ صَوْمُ دَاوُدَ» قَالَ فَكَيْفَ بِمَنْ يَصُومُ يَوْمًا وَيُفْطِرُ يَوْمَيْنِ؟ قَالَ «وَدِدْتُ أَنِّي أُطِيقُ ذَاكَ» قَالَ ثُمَّ قَالَ «ثَلَاثٌ مِنْ كُلِّ شَهْرٍ وَرَمَضَانُ إِلَى رَمَضَانَ هَذَا صِيَامُ الدَّهْرِ كُلَّهُ»