Significance of the six days of Shawwal

Abu Ayyub Al-Ansari relates that Allah’s Messenger (peace be upon him) says: “Whoever fasts the month of Ramadan and then follows it with six days of fasting in the month of Shawwal, it will be as if he had fasted the year through.” (Sahih Muslim, 1163)
The month of Shawwal is singled out for the observance of extra fasts, since this month follows immediately after Ramadan. The six days of voluntary fasting are to the obligatory fast of Ramadan what the Sunnah prayers are to the obligatory prayers.