Did the Prophet (peace be upon him) instruct us to fast the day of Tasu'a along with the day of Ashura?

It is desirable to fast the ninth and tenth days of Muharram. Fasting the tenth alone is permissible, and fasting the ninth along with it is better. The wisdom behind fasting the ninth with the tenth is to differ from the Jews, who only fast the tenth, and to connect the day of Ashura with a fast before it, and to be cautious in fasting the tenth in case of an incomplete new moon or an error in counting the days. The strongest of these reasons is to differ from the People of the Book.