(35) بَاب النَّهْيِ عَنْ صَوْمِ الدَّهْرِ لِمَنْ تَضَرَّرَ بِهِ أَوْ فَوَّتَ بِهِ حَقًّا أَوْ لَمْ يُفْطِرْ الْعِيدَيْنِ وَالتَّشْرِيقَ وَبَيَانِ تَفْضِيلِ صَوْمِ يَوْمٍ وَإِفْطَارِ يَوْمٍ
'Abdullah b. 'Amr (Allah be pleased with them) reported that the Messenger of Allah (ﷺ) said to me! 'Abdullah b. 'Amr, it has been conveyed to me that you observe fast during the day and stand in prayer during the whole night. Don't do that, for your body has a share of its own in you, your eye has a share of its own in you, your wife has a share of her own in you. Observe fast and break it too. Fast for three days in every month and that is a prepetual fasting. I said! Messenger of Allah, I have got strength enough (to do more than this), whereupon he said:
Then observe the fast of David (peace be upon him). Observe fast one day and break it (on the other) day. And he ('Abdullah b. 'Amr) used to say: Would that I had availed myself of this concession.
Reference: Sahih Muslim 1159 o
In-book reference: Book 13, Hadith 249
USC-MSA web (English) reference(deprecated numbering scheme): Book 6, Hadith 2599