al-Fadl bin Musa al-Synany الفضل بن موسى السيناني · The Book of Fasting

'The month of Ramadan. He said: "I heard the Messenger of Allah say: In it the gates of Paradise are opened and the gates of the Fire are closed, and the devils are chained up, and a caller calls out every night: O doer of good, proceed; O doer of evil, desist!"'

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.