The Best in Fasting Ashura and the Ruling on Fasting It Alone

Question:
He says: Honorable Shaykh, may Allah grant you success, what is the best regarding fasting the day of Ashura? We have heard some say that the best is to fast three days, and we have heard others say that the best is to fast the ninth along with the tenth. Also, what is the ruling on fasting the day of Ashura alone? Some say it is permissible, some say it is disliked, and some say it is forbidden?

Answer:
We are not concerned with what so-and-so says or what so-and-so says. We are concerned with the words of the Messenger (peace and blessings be upon him): "Fast a day before it, differ from the Jews" and the tenth. So we act according to the saying of the Messenger (peace and blessings be upon him): we fast the ninth and the tenth. This is what we act upon. As for what so-and-so said or what so-and-so said, we are not concerned with that. Yes.