Six Days of Shawwal in Other Months

Q: Will I attain the same virtue and reward of fasting the six days of Shawwāl if I fast six days outside of Shawwāl?

A: The apparent position of the madhhab is that the virtue is not attained by fasting them outside of Shawwāl, based on the outward meaning of the reports, and this was explicitly affirmed by many of the companions of the school.

There is, however, a consideration that some scholars held the virtue may still be attained outside of Shawwāl, based on the multiplication of deeds tenfold and that the specification of Shawwāl relates to ease and encouragement following Ramadan.

This view, however, was regarded as weak and contrary to the hadith. Rather, the six days are specifically tied to Shawwāl as an extension of Ramadan, not merely due to the general multiplication of rewards.

It is further noted that the virtue may be attained for one who fasts them and makes up missed Ramadan fasts due to a valid excuse, and this is likely what the companions intended.

Source: al-Inṣāf, Kashshāf al-Qināʿ, al-Furūʿ wa Taṣḥīḥ al-Furūʿ