Sunan an-Nasa'i 2372
سنن النسائي#2372SahihIt 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-Hijjah and three days each month: The first Monday of the month, and two Thursday
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiIsnaad Sahih
In-book reference: 22:283