Sahih Muslim 1159 a
'Abdullah b. 'Amr b. al-'As reported that the Messenger of Allah (ﷺ) was informed that he could stand up for (prayer) throughout the night and observe fast every day so long as he lived. Thereupon the Messenger of Allah (ﷺ) said:
Is it you who said this? I said to him: Messenger of Allah, it is I who said that. Thereupon the Messenger of Allah may peace be upon him) said: You are not capable enough to do so. Observe fast and break it; sleep and stand for prayer, and observe fast for three days during the month; for every good is multiplied ten times and this is like fasting for ever. I said: Messenger of Allah. I am capable of doing more than this. Thereupon he said: Fast one day and do not fast for the next two days. I said: Messenger of Allah, I have the strength to do more than that. The Prophet (ﷺ), said: Fast one day and break on the other day. That is known as the fasting of David (peace be upon him) and that is the best fasting. I said: I am capable of doing more than this. Thereupon the Messenger of Allah (ﷺ) said: There is nothing better than this. 'Abdullah b. 'Amr (Allah be pleased with them) said: Had I accepted the three days (fasting during every month) as the Messenger of Allah (ﷺ) had said, it would have been more dear to me than my family and my property.
حَدَّثَنِي أَبُو الطَّاهِرِ، قَالَ سَمِعْتُ عَبْدَ اللَّهِ بْنَ وَهْبٍ، يُحَدِّثُ عَنْ يُونُسَ، عَنِ ابْنِ، شِهَابٍ ح وَحَدَّثَنِي حَرْمَلَةُ بْنُ يَحْيَى، أَخْبَرَنَا ابْنُ وَهْبٍ، أَخْبَرَنِي يُونُسُ، عَنِ ابْنِ شِهَابٍ، أَخْبَرَنِي سَعِيدُ بْنُ الْمُسَيَّبِ، وَأَبُو سَلَمَةَ بْنُ عَبْدِ الرَّحْمَنِ أَنَّ عَبْدَ اللَّهِ بْنَ عَمْرِو بْنِ الْعَاصِ، قَالَ أُخْبِرَ رَسُولُ اللَّهِ صلى الله عليه وسلم أَنَّهُ يَقُولُ لأَقُومَنَّ اللَّيْلَ وَلأَصُومَنَّ النَّهَارَ مَا عِشْتُ ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ آنْتَ الَّذِي تَقُولُ ذَلِكَ ‏"‏ ‏.‏ فَقُلْتُ لَهُ قَدْ قُلْتُهُ يَا رَسُولَ اللَّهِ ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ فَإِنَّكَ لاَ تَسْتَطِيعُ ذَلِكَ فَصُمْ وَأَفْطِرْ وَنَمْ وَقُمْ وَصُمْ مِنَ الشَّهْرِ ثَلاَثَةَ أَيَّامٍ فَإِنَّ الْحَسَنَةَ بِعَشْرِ أَمْثَالِهَا وَذَلِكَ مِثْلُ صِيَامِ الدَّهْرِ ‏"‏ ‏.‏ قَالَ قُلْتُ فَإِنِّي أُطِيقُ أَفْضَلَ مِنْ ذَلِكَ ‏.‏ قَالَ ‏"‏ صُمْ يَوْمًا وَأَفْطِرْ يَوْمَيْنِ ‏"‏ ‏.‏ قَالَ قُلْتُ فَإِنِّي أُطِيقُ أَفْضَلَ مِنْ ذَلِكَ يَا رَسُولَ اللَّهِ قَالَ ‏"‏ صُمْ يَوْمًا وَأَفْطِرْ يَوْمًا وَذَلِكَ صِيَامُ دَاوُدَ - عَلَيْهِ السَّلاَمُ - وَهُوَ أَعْدَلُ الصِّيَامِ ‏"‏ ‏.‏ قَالَ قُلْتُ فَإِنِّي أُطِيقُ أَفْضَلَ مِنْ ذَلِكَ ‏.‏ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ لاَ أَفْضَلَ مِنْ ذَلِكَ ‏"‏ ‏.‏ قَالَ عَبْدُ اللَّهِ بْنُ عَمْرٍو رضى الله عنهما لأَنْ أَكُونَ قَبِلْتُ الثَّلاَثَةَ الأَيَّامَ الَّتِي قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم أَحَبُّ إِلَىَّ مِنْ أَهْلِي وَمَالِي ‏.‏