One of the days that is unlawful to fast
3. صوم يوم الشك
Fasting the Day of Doubt
وهو يوم الثلاثين من شعبان، حيث يشك فيه الناس: هل هومن شعبان أو من رمضان؟ وحيث لا تثبت رؤية الهلال فيه. فلا يجوز صومه، بل ينبغي اعتباره يوما متبقيا من شعبان.
This is when it is the 30th day of Shaʿbān and the people are in doubt: is this day part of Shaʿbān or part of Ramaḍān? Furthermore, no sighting of the crescent moon has been confirmed. It is thus not permissible to fast this day. Rather, it should be considered a remaining day of Shaʿbān.
ودليل تحريم صيامه ما رواه أبو داود (2334) والترمذي (686) – وصحّحه – عن عمار بن ياسر رضي الله عنه عن رسول الله صلى الله عليه وسلم، قال: {من صام اليوم الذي يَشك فيه الناس فقد عصى أبا القاسم}
The evidence for its being unlawful to fast this day is what has been related by Abū Dāwūd (2334) and at-Tirmidhī (686) – and he declared it authentic – on the authority of ʿAmmār ibn Yāsir, may Allah be pleased with him, from the Messenger of Allah, may Allah bless him and grant him peace, who said: {Whoever fasts the day that the people have doubt about has indeed disobeyed Abū al-Qāsim [i.e. the Messenger of Allah, may Allah bless him and grant him peace].}
[Translated from Al-Fiqh al-Manhajī ʿalā Madhhab al-Imām ash-Shāfiʿī by Imams Muṣṭafā al-Bughā, ʿAlī ash-Sharbajī and Muṣṭafā al-Khin (Damascus: Dār al-ʿUlūm al-Insāniyyah, 1410/1989), v.2, p.103]
