Musa ibn Talha · The Book of Fasting

"There are four things which the Prophet never gave up: Fasting 'Ashura', (fasting during) the ten days, (fasting) three days of each month, and praying two Rak'ahs before Al-Ghadah (Fajr)."

the Messenger of Allah used to fast nine days of Dhul-Hijjah, the day of 'Ashura', and three days of each month: The first Monday of the month, and two Thursday.

"The Prophet used to fast the ten (days), and three days of each month: Monday and Thursday."

"The Messenger of Allah used to enjoin fasting three days: The first Thursday, and Monday and Monday."

"Fasting three days of each month is fasting for a lifetime, and the shining days of Al-Bid, the thirteenth, fourteenth and fifteenth."

"A Bedouin came to the Prophet with a rabbit that he had grilled it and placed it in front of him. The Messenger of Allah refrained from eating, but he told the people to eat. The Bedouin also refrained, and the Prophet said to him: 'What is keeping you from eating?' He said: 'I fast three days of the month.' He said: 'If you was to fast, fast the shining days."'

"The Messenger of Allah commanded us to fast the three days of Al-Bid, the thirteenth, fourteenth and fifteenth."

"The Messenger of Allah commanded us to fast three days of Al-Bid, the thirteenth, fourteenth and fifteenth."

"I heard Abu Dharr, at Ar-Rabadhah, saying: 'The Messenger of Allah said: if you want to fast at any time during the monthm then fast on the thirteenth, fourteenth and fifteenth."'