Wa `alaykum as-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Fasting six days of Shawwal, after the day of Eid, is a Sunnah which means that it is not sin for a Muslim who used to observe fasting these six days each year not to fast them.
With regard to your question, The Standing Committee for Islamic Research and Iftaa’ in Saudi Arabia states:
Fasting six days of Shawwal, after the day of Eid, is a Sunnah. Prophet Muhammad (peace and blessings be upon him) is reported to have said, “Whoever fasts during the month of Ramadan and then follows it with six days of Shawwal will be (rewarded) as if he had fasted the entire year” (Muslim)
It is not wajib (obligatory) on the person who does this once or more often to continue doing it. He is not guilty of a sin if he does not fast these days.
Source: Excerpted with modifications from, www.islamqa.info
Moreover, the prominent Muslim scholar and da`iyah Zeinab Mostafa adds:
I commend you for your interest and keenness on observing the Sunnah of the Prophet (peace and blessings be upon him) in fasting the six days of Shawwal. You should know that fasting on those days is a sunnah, which means that it is not mandatory but it is highly recommended and there is a great reward promised by the Prophet (peace and blessings be upon him) for observing the fast.
Therefore, it is optional to repeat this practice or discontinue it, but it is preferred to continue fasting every year and to maintain a high level of iman (faith) after Ramadan.
Allah Almighty knows best.
Editor’s note: This fatwa is from Ask the Scholar’s archive and was originally published at an earlier date.