(83) باب كَيْفَ يَصُومُ ثَلاَثَةَ أَيَّامٍ مِنْ كُلِّ شَهْرٍ وَذِكْرِ اخْتِلاَفِ النَّاقِلِينَ لِلْخَبَرِ فِي ذَلِكَ .
It was narrated from Ibn 'Umar that:
the Messenger of Allah used to fast three days of each month: Monday at the beginning of the month, the following Thursday, then the Thursday after that. (DE)
Reference (DE): Sunan an-Nasa'i 2414 (DE)
In-book reference (DE): Book 22, Hadith 325 (DE)
English translation (DE): Vol. 3, Book 22, Hadith 2416 (DE)