(70) باب صَوْمِ النَّبِيِّ صلى الله عليه وسلم - بِأَبِي هُوَ وَأُمِّي - وَذِكْرِ اخْتِلاَفِ النَّاقِلِينَ لِلْخَبَرِ فِي ذَلِكَ
It was narrated from Hunaidah bin Khalid that his wife said:
"One of the wives of the Prophet said: "The Prophet used to fast on the day of 'Ashura, nine days of Dhul-Hijjiah and three days each month: The first Monday of the month, and two Thursday."
Reference: Sunan an-Nasa'i 2372
In-book reference: Book 22, Hadith 283
English translation: Vol. 3, Book 22, Hadith 2374