Observing Sawm on the White Days

Q: Is it permissible to observe Sawm (Fast) of the White Days (13th, 14th, and 15th of every Hijri month) on days other than their fixed days during the same month?

A: The voluntary Sawm of three days in every month is one of the best acts of `Ibadah (worship). The Prophet (peace be upon him) advised Abu Hurayrah and Abu Dhar (may Allah be pleased with them) to do so. He said to Abu Dhar: If you want to observe Sawm on three days in the (Hijri) month then let it be on the thirteenth, fourteenth and fifteenth. (Related by Al-Nasa'y and Al-Tirmidhy) Al-Tirmidhy ranked the Hadith as Hasan (a Hadith whose chain of narration contains a narrator with weak exactitude, but is free from eccentricity or blemish). These are the White Days. However, if the person observes Sawm on three days at the beginning, end, or middle of the month, it is valid to do so.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.