540 – ʿAmmār ibn Yāsir (may Allah be pleased with him) said: “Whoever fasts on the day about which there is doubt has disobeyed Abū al-Qāsim ﷺ.” Al-Bukhārī cited the report in suspended form, the Five connected its chain, and Ibn Khuzaymah and Ibn Ḥibbān declared it authentic (1).
Grade of the hadith
This hadith is ṣaḥīḥ (authentic). It was recorded by Abū Dāwūd, al-Tirmidhī, and al-Nasāʾī. Al-Tirmidhī remarked, “The ḥadith of ʿAmmār is sound, and this is the position of most scholars among the Companions of the Prophet ﷺ and those who followed them.” Al-Dāraquṭnī said, “Its chain is sound and all its transmitters are trustworthy.” It was likewise authenticated by al-Bayhaqī, al-ʿIrāqī, and al-Ḥākim, and al-Dhahabī concurred. Ibn ʿAbd al-Barr stated, “Among the hadith scholars it is considered musnad and marfūʿ, and there is no disagreement about that.”
Vocabulary of the hadith
• “about which there is doubt”: The relative pronoun is used instead of the explicit phrase “the day of doubt” to emphasize that fasting even a day in which there is the slightest uncertainty constitutes disobedience to Abū al-Qāsim ﷺ.
• “about which there is doubt”: a passive construction meaning the day whose status is unclear—whether it is the first of Ramadan or the last of Shaʿbān, namely the thirtieth of Shaʿbān when the crescent is obscured.
• “Abū al-Qāsim”: the kunyah of the Prophet ﷺ, derived from his eldest son.