Sahih Bukhari 1977

حَدَّثَنَا عَمْرُو بْنُ عَلِيٍّ ، أَخْبَرَنَا أَبُو عَاصِمٍ ، عَنِ ابْنِ جُرَيْجٍ ، سَمِعْتُ عَطَاءً ، أَنَّ أَبَا الْعَبَّاسِ الشَّاعِرَ أَخْبَرَهُ ، أَنَّهُ سَمِعَ عَبْدَ اللَّهِ بْنَ عَمْرٍو رَضِيَ اللَّهُ عَنْهُ ، بَلَغَ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ : أَنِّي أَسْرُدُ الصَّوْمَ وَأُصَلِّي اللَّيْلَ ، فَإِمَّا أَرْسَلَ إِلَيَّ ، وَإِمَّا لَقِيتُهُ ، فَقَالَ : أَلَمْ أُخْبَرْ أَنَّكَ تَصُومُ وَلَا تُفْطِرُ وَتُصَلِّي وَلَا تَنَامُ ، فَصُمْ وَأَفْطِرْ ، وَقُمْ وَنَمْ ، فَإِنَّ لِعَيْنِكَ عَلَيْكَ حَظًّا ، وَإِنَّ لِنَفْسِكَ ، وَأَهْلِكَ عَلَيْكَ حَظًّا ، قَالَ : إِنِّي لَأَقْوَى لِذَلِكَ ، قَالَ : فَصُمْ صِيَامَ دَاوُدَ عَلَيْهِ السَّلَام ، قَالَ : وَكَيْفَ ؟ قَالَ : كَانَ يَصُومُ يَوْمًا وَيُفْطِرُ يَوْمًا ، وَلَا يَفِرُّ إِذَا لَاقَى ، قَالَ : مَنْ لِي بِهَذِهِ يَا نَبِيَّ اللَّهِ ، قَالَ عَطَاءٌ : لَا أَدْرِي كَيْفَ ذَكَرَ صِيَامَ الْأَبَدِ ، قَالَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ : لَا صَامَ مَنْ صَامَ الْأَبَدَ مَرَّتَيْنِ .

Narrated `Abdullah bin `Amr: The news of my daily fasting and praying every night throughout the night reached the Prophet. So he sent for me or I met him, and he said, I have been informed that you fast everyday and pray every night (all the night). Fast (for some days) and give up fasting (for some days); pray and sleep, for your eyes have a right on you, and your body and your family (i.e. wife) have a right on you. I replied, I have more power than that (fasting). The Prophet said, Then fast like the fasts of (the Prophet) David . I said, How? He replied, He used to fast on alternate days, and he used not to flee on meeting the enemy. I said, From where can I get that chance? (`Ata' said, I do not know how the expression of fasting daily throughout the life occurred. ) So, the Prophet said, twice, Whoever fasts daily throughout his life is just as the one who does not fast at all.