Anyone who maintains that fasting on it was not obligatory must accept one of two conclusions: either its recommended status was abandoned, so that it was no longer recommended, or ‘Abd Allāh ibn Mas‘ūd said this on the basis of his own opinion, unaware that fasting on it was recommended. The latter is unlikely, for the Prophet (peace and blessings be upon him) encouraged them to fast on it and stated that doing so expiates the sins of the preceding year (1). The Companions continued to fast on it until his death, and not a single word has been transmitted from him prohibiting it or indicating that fasting on it was disliked (2). It is therefore clear that what was abandoned was its obligatory status, not its recommended status.
If it is said: “The hadith of Mu‘āwiyah recorded in both collections of authentic hadith explicitly states that it was not obligatory and had never been prescribed as an obligation.”
The answer is that Mu‘āwiyah’s hadith explicitly denies that its obligation continued and establishes that it was no longer obligatory at that time. It does not rule out an earlier obligation that was subsequently abrogated. There is nothing to prevent one from saying of something that was once obligatory, but whose obligation was abrogated: “Allah has not prescribed it for us” (3).
A second answer is that, at most, the negation encompasses both the past and the present. Its scope is then restricted by the evidence establishing its obligation in the past, leaving the negation to apply to the continuation of that obligation.
A third answer is that he (peace and blessings be upon him) denied only that its obligatory status was established through the Quran. He indicated this by saying: “Allah has not prescribed it for us.” This does not rule out its being obligatory on another basis. An obligation that Allah has prescribed for His servants is one that He has told them He prescribed for them, as in His words:
“Fasting has been prescribed for you” [al-Baqarah: 183].
Thus, the Prophet (peace and blessings be upon him) stated