Ramadan and then follows it with six days of Shawwal.”¹ Those six days may well include a Saturday.

He likewise commanded fasting on the “white days”²—the thirteenth, fourteenth, and fifteenth of every lunar month—and they too can fall on a Saturday. Similar instances are many.

Thus al-Athram gathered from Abu ʿAbd Allah’s words that he withheld from acting on that ḥadīth and regarded fasting on Saturday as permissible. Al-Athram cited the very report advanced to support the view of dislike, and added that the leading critic of ḥadīth defects, Yahya ibn Saʿid, used to avoid it and refused to transmit it—an implicit weakening of the report.

Al-Athram further argued from the numerous, well-attested texts that clearly endorse fasting on Saturday.

Nor should it be said that the prohibition concerns only fasting Saturday by itself, for the wording states: “Do not fast on Saturday except for what has been made obligatory upon you.” The phrase “except” shows that the ruling encompasses every type of fast on that day. Had the intention been limited to singling Saturday out, the obligatory fast would never have been included in the first place, since an obligatory fast cannot be an isolated one; its explicit exclusion therefore proves that voluntary fasts are meant. This differs from the case of Friday, where the Prophet ﷺ explained that the prohibition applies solely to fasting it alone.

Accordingly, the ḥadīth is either irregular and not reliably preserved, or it has been abrogated. This was the approach of Aḥmad’s early companions who accompanied him, such as al-Athram and Abu Dawud.

¹ “Whoever fasts Ramadan and then follows it with six days of Shawwal.”
² The 13th, 14th, and 15th of each lunar month.