Which is better regarding the Ashura fast?

It is authentically reported in Sahih Muslim on the authority of Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) resolved to fast the ninth day along with the tenth, in order to differ from the Jews, but he passed away before the next year. The scholars have mentioned three levels for fasting the Day of Ashura: the most complete is fasting the day before it and the day after it; next is fasting the ninth and the tenth; and then, fasting the tenth alone. As for fasting the ninth alone, it has no basis.