قَالَ لِي رَسُولُ اللَّهِ صلى الله عليه وسلم " أَلَمْ أُنَبَّأْ أَنَّكَ تَقُومُ اللَّيْلَ وَتَصُومُ ". فَقُلْتُ نَعَمْ. فَقَالَ " فَإِنَّكَ إِذَا فَعَلْتَ ذَلِكَ هَجَمَتِ الْعَيْنُ وَنَفِهَتِ النَّفْسُ، صُمْ مِنْ كُلِّ شَهْرٍ ثَلاَثَةَ أَيَّامٍ، فَذَلِكَ صَوْمُ الدَّهْرِ ـ أَوْ كَصَوْمِ الدَّهْرِ ". قُلْتُ إِنِّي أَجِدُ بِي ـ قَالَ مِسْعَرٌ يَعْنِي ـ قُوَّةً. قَالَ " فَصُمْ صَوْمَ دَاوُدَ ـ عَلَيْهِ السَّلاَمُ ـ وَكَانَ يَصُومُ يَوْمًا، وَيُفْطِرُ يَوْمًا، وَلاَ يَفِرُّ إِذَا لاَقَى ".
The Prophet (ﷺ) said to me, "I have been informed that you pray all the nights and observe fast all thedays; is this true?" I replied, "Yes." He said, "If you do so, your eyes will become weak and you willget bored. So fast three days a month, for this will be the fasting of a whole year, or equal to thefasting of a whole year." I said, "I find myself able to fast more." He said, "Then fast like the fastingof (the Prophet) David who used to fast on alternate days and would not flee on facing the enemy."