Fasting According To the Five Schools of Islamic Law

Supererogatory Fasts

Fasting is considered mustahabb on all the days of the year except those on which it has been prohibited. But there are days whose fast has been specifically stressed and they include three days of each month, preferably the `moonlit' days (al-'ayyam al-bid), which are the thirteenth, fourteenth and fifteenth of each lunar month.

Among them is the day of `Arafah (9th of Dhu al-Hijjah). Also emphasized is the fasting of the months of Rajab and Sha'ban. Fasting on Mondays and Thursdays has also been emphasized. There are other days as well which have been mentioned in elaborate works. There is consensus among all the schools that fasting on these days is mustahabb.