And its chain of transmission is authentic, though mursal. ʿAbd al-Razzāq also narrated it (7852) from ʿAṭāʾ as a mursal report. Al-Haythamī has documented other hadiths on this subject in Majmaʿ al-Zawāʾid; whoever wishes to know more may refer to it. Another version contains a rejected addition: “Complete the rest of your day and make it up later.” Its chain contains an unidentified narrator. For that reason, I included it in the eleventh volume of al-Ḍaʿīfah, no. 5199, and in Ḍaʿīf Abī Dāwūd, no. 422.

Jurisprudential Points from the Hadith

This hadith contains two important points. The first is that fasting the day of ʿĀshūrāʾ was initially an obligation. This is apparent from the emphasis placed upon it in the report: the public proclamation commanding its observance, the instruction that those who had eaten on that day abstain from food, and the command that he fast the remainder of the day. For a voluntary fast cannot entail abstaining after one has broken the fast, as Ibn al-Qayyim—may Allah have mercy on him—said in Tahdhīb al-Sunan (3/327).

Other hadiths confirm that it was obligatory, and that when fasting the month of Ramadan was prescribed, it became the obligatory fast, as stated in the hadith of ʿĀʾishah recorded by al-Bukhārī and Muslim and others. It is cited in Ṣaḥīḥ Abī Dāwūd, no. 2110.

The second is that anyone upon whom fasting becomes obligatory during the day—such as an insane person who regains consciousness, a minor who reaches puberty, a disbeliever who embraces Islam, or someone who receives the news that the crescent of Ramadan was sighted the previous night—may form the intention during the day when the obligation arises, even if they have already eaten or drunk. This case is therefore an exception to the general import of the Prophet’s saying, peace and blessings be upon him: “Whoever has not firmly intended to fast before dawn has no valid fast.” This is an authentic hadith, as I have established in Ṣaḥīḥ Abī Dāwūd (2118). And this view—