(82) باب ذِكْرِ الاِخْتِلاَفِ عَلَى أَبِي عُثْمَانَ فِي حَدِيثِ أَبِي هُرَيْرَةَ فِي صِيَامِ ثَلاَثَةِ أَيَّامٍ مِنَ كُلِّ شَهْرٍ
It was narrated that Abu Hurairah said:
" I heard the Messenger of Allah say: 'The month of patience ( Ramadan) and three days of each month is fasting for a lifetime."' (Sahih).
Reference: Sunan an-Nasa'i 2408
In-book reference: Book 22, Hadith 319
English translation: Vol. 3, Book 22, Hadith 2410