Question: Is it correct to fast the day of ‘Aashooraa by itself? And what is the ruling regarding the one who does so out of ignorance?
Response: Yes, it is correct to fast [the day of] ‘Aashooraa by itself, and he will be rewarded for that [in shaa.-Allaah].
Because the Prophet (sal-Allaahu ’alayhi wa sallam) said regarding the fast of ‘Aashooraa:
«I hope Allaah will expiate thereby for the year that came before it.»
However, some of the scholars dislike that it be singled out, meaning to fast the [day of the] tenth [of Muharram] by itself, and not to fast the day before it, nor the day after it.
Some of the scholars dislike that [it be singled out]. They explained that the last of the two commands of the Messenger of Allaah (sal-Allaahu ’alayhi wa sallam) [regarding this] was that he said:
«Differ from the Jews, [so] fast the day before it, or the day after it.»
And he [also] said:
«If I live until next year, I will certainly fast the ninth [day of Muharram].»
So based upon this, we say to the brother – fast the day before it or the day after it.
Question: If he has any fasts to make up from Ramadhaan, should he fast the day of ‘Aashooraa?
Response: Yes, yes. Whoever has any fasts to make up from Ramadhaan, should fast the day of ‘Aashooraa, and [likewise] fast the day of ‘Arafah, and fast the [three] full moon days.
However, it is better that he begins with that which is obligatory [upon him]. Yes.