There is another difficulty: it is established in the two Sahīh collections (1) that al-Ash‘ath ibn Qays came in to see ‘Abdullāh ibn Mas‘ūd while he was eating lunch. Ibn Mas‘ūd said: “Abū Muhammad, come and join me for lunch.” He replied: “Is today not ‘Āshūrā’?” Ibn Mas‘ūd said: “Do you know what ‘Āshūrā’ is?” He asked: “What is it?” Ibn Mas‘ūd replied: “It is simply a day that the Messenger of Allah (peace and blessings be upon him) used to fast before fasting Ramadan was prescribed. Once fasting Ramadan was prescribed, he stopped fasting it.”
Muslim also narrated in his Sahīh (2), from Ibn ‘Abbās, that when the Messenger of Allah (peace and blessings be upon him) fasted on ‘Āshūrā’ or instructed others to fast it, they said: “O Messenger of Allah, it is a day held in honour by the Jews and Christians.” The Messenger of Allah (peace and blessings be upon him) said: “Next year, Allah willing, we shall fast the ninth day.” But the Messenger of Allah (peace and blessings be upon him) died before the following year came.
This indicates that he fasted it and instructed others to fast it a year before his death, whereas the earlier hadith narrated by Ibn ‘Abbās indicates that this occurred upon his arrival in Medina. Moreover, Ibn Mas‘ūd stated that fasting ‘Āshūrā’ was abandoned when fasting Ramadan was prescribed, which conflicts with the aforementioned hadith of Ibn ‘Abbās. Nor can it be said that only the obligation to fast it was discontinued, since it had never been made obligatory. For it is established in the two Sahīh collections (3) that Mu‘āwiyah ibn Abī Sufyān said: “I heard the Messenger of Allah (peace and blessings be upon him) say: ‘This is the day of ‘Āshūrā’. Allah has not prescribed fasting it for you, but I am fasting. Whoever wishes may fast (4), and whoever wishes may refrain from fasting.’” Mu‘āwiyah certainly heard this only after the Conquest.