أَخْبَرَنَا زَكَرِيَّا بْنُ يَحْيَى، قَالَ حَدَّثَنَا عَبْدُ الأَعْلَى، قَالَ حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ، عَنْ ثَابِتٍ، عَنْ أَبِي عُثْمَانَ، أَنَّ أَبَا هُرَيْرَةَ، قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏"‏ شَهْرُ الصَّبْرِ وَثَلاَثَةُ أَيَّامٍ مِنْ كُلِّ شَهْرٍ صَوْمُ الدَّهْرِ ‏"‏ ‏.‏
Translation
It was narrated that Abu Dharr said

"The Messenger of Allah said: 'Whoever fasts for three days of each month, he has fasted for a whole lifetime.' Then he said: Allah has spoken the truth in His book: Whoever brings a good deed shall have ten times the like thereof to his credit.