The following hadiths reside in hadith books about the six days of fasting in Shawwal:
“A person who performs fasting in Ramadan and then adds six more days in Shawwal is regarded as if he has performed fasting in the whole year (in terms of reward).” (Muslim, Sawm, 204 (1164))
“Whoever performs fasting in Ramadan and adds six more days to it in Shawwal is regarded as if he has performed fasting during the whole year.” (Tirmidhi, Siyam, 53)
“If a person fasts the whole Ramadan and then six days in Shawwal, it is regarded as if that person has spent the whole year fasting.” (Abu Dawood, Savm, 58)
“Whoever fasts Ramadan, and then six days after Eid, it is [like fasting] an entire year. Whoever does a good deed shall have ten times its reward.” (Ibn Majah, Siyam, 33)
Explanation About Hadiths:
Imam Shafi’i, Ahmed b. Hanbel, Dawood Dhahiri and a group of more scholars consider the six days of fasting in Shawwal as mustahab – desirable.
Imam Abu Hanifah, Imam Malik and Abu Yusuf on the other hand, think that fasting in Shawwal for six days is makruh – disliked. According to Imam Malik’s explanation in Muwatta, this fast is bid’at since nobody performed this type of fasting before him and therefore it is makruh. He also adds that he is afraid of uneducated people to consider this fasting as of the fast in Ramadan.
Here is Imam Malik’s explanation:
“I have met no scholars or faqihs that fast for six days after Eid, and I haven’t inherited any narrations from any of my forerunners on this subject. Besides, scholars find the fasting in Shawwal as makruh since they fear that uneducated people may consider these six days as if from Ramadan and may make a bid’at up. If scholars had permitted it, they would have been seen as fasting for six days after Eid.” (Muwatta, The explanation residing at the end of section Sawm)
Some Hanafi and Maliki books, on the other hand, mention fasting for six days in Shawwal as mandub – commendable. For example, six days of fast in Shawwal is mentioned amongst the mandub fasts in Noor-ol-Izah and Sharh-ul Maraq’ul. In the postscript of Maraq-ul Falah, Tahtavi narrates that it is mentioned in Bahr: “Fasting six days in Shawwal is makruh, either it is consecutive or separate six days according to Imam Hanafi, however some scholars have seen no harm in it later on”.
Ibn Abidin also mentions that scholars after Imam Hanafi had considered no harm in this fasting of six days.
As understood from the above explanation, fasting for six days in Shawwal is mandub – commendable according to most of Islam scholars. There is no difference between this fast being consecutive or separate. (Sunan Abu Dawood Translation and Sharh, Necati Yeniel, Hüseyin Kayapınar, Necat Akdeniz, Şamil Press, İstanbul, 1989, v: 9, p: 348-349.)