It is recommended to keep six fasts in the month of Shawwal which is the following month after Ramadan. The Holy Prophet (s.a.w) has said:
“Whoever completes fasts of Ramadan then adds to them the fast of six days in the month Shawwal, it will carry the reward of fasting for the whole year.” (Sahih Muslim)
This hadith had described the great thawab (reward) of six fasts of Shawwal. The scholars have interpreted this hadith by saying that according to the recognized rules of Shari’ah every good deed is rewarded ten times more thawab of its origin, therefore the thawab of 30 days of Ramadan amounts to the thawab of fasting for 300 days. If the fasts of Ramadan are followed by six more fasts, they carry the thawab of 60 days more thus raising the total thawab to 360 which is the number of days of one year according to Islamic calendar.
Therefore we should take this opportunity of acquiring such an enormous reward from Allah. It is more preferable to start these fasts from the 2nd of Shawwal and keep fasting upto the 7th of Shawwal. However if they are kept in other days, it is hoped that the requirement of the above may also be fulfilled.