As for a day of clear skies, in his view it is either a day of doubt or a day certainly belonging to Shaʿbān; fasting on it is prohibited without hesitation. The principles of Islamic law support this position more strongly than any other. When there is doubt about whether something is obligatory—as when someone doubts whether zakah, an expiation, a prayer, or anything else is due—it need not be performed, but neither is refraining from it recommended. Rather, performing it as a precaution is recommended. Thus, the principles of Islamic law neither prohibit taking precautions nor impose an obligation merely on account of doubt.

Furthermore, the beginning of the month is like the beginning of the day. If someone doubts whether dawn has broken, he is neither obliged to abstain nor prohibited from abstaining with the intention of fasting. Moreover, cloud cover at the beginning of the month is comparable to the obscurity arising from doubt. Rather, fasting on the day of doubt is prohibited for fear of adding to the obligatory fast.

This position reconciles most of the reports transmitted from the Companions on this subject. The groups among them who fasted—such as ʿUmar, ʿAlī, Muʿāwiyah, and others—did not explicitly declare it obligatory, while most of those who refrained did not explicitly declare it prohibited.

Perhaps those among them who disapproved of fasting only disapproved of it for someone who believed it obligatory, fearing that something not obligatory would be made obligatory. Similarly, some of them disapproved of cleansing oneself with water after relieving oneself when they feared that a person might come to believe it obligatory. Likewise, a group of them instructed someone who fasted while travelling to make up the fast because they thought he disapproved of breaking his fast while travelling. The disapproval would thus relate to the circumstances of the person performing the act, not to taking the precaution of fasting itself. For prohibiting fasting or making it obligatory