“None of you should fast on Friday unless he fasts a day before it or a day after it.”
Narrated by al-Bukhārī (no. 1985), with the wording being his, and Muslim (no. 1144), from the ḥadīth of Abū Hurayrah (may Allah be pleased with him).
Brief Explanation of the Hadith
The Sharīʿah encourages voluntary fasting and clarifies its immense reward. However, despite its virtue, it forbids singling out certain days for fasting without a legislated reason. Among that is his statement (may Allah’s peace and blessings be upon him): “None of you should fast on Friday…”—that is, he should not single it out for fasting by itself. The scholars understood this prohibition to indicate dislike (karāhah) rather than strict prohibition (taḥrīm). This dislike is removed when the meaning of singling it out no longer applies, and that occurs in two situations:
The first: that one fasts a day before it or a day after it—such as fasting Thursday or Saturday along with Friday. This is what is intended by his statement: “…unless he fasts a day before it or a day after it.”
The second: that Friday coincides with a habitual fast—such as one who fasts every other day—or that it happens to fall on a legislated day of fasting like ʿArafah or ʿĀshūrāʾ, or a vowed fast. For example, if someone vowed to fast on the day Zayd arrives, and his arrival happened to be on a Friday, then there is no dislike in fasting it, since there was no intention to single it out. This is supported by his statement (may Allah’s peace and blessings be upon him): “Do not single out Friday for fasting among the days…”
The wisdom behind prohibiting singling out Friday for fasting is that Friday is a comprehensive day of worship, in which acts of devotion gather in a way that they do not on other days. Among them are: performing ghusl, going early to the prayer, waiting for it, listening attentively to the khuṭbah, and increasing in remembrance afterward. Thus, breaking the fast is more helpful in carrying out these duties without weakness or weariness. This is similar to the Sunnah concerning the pilgrim on the Day of ʿArafah, for whom it is recommended to refrain from fasting so that he may strengthen himself for the great acts of worship of that day.
It is also possible that the prohibition is because Friday is the weekly ʿĪd, and a day of ʿĪd is a time of gratitude and joy. Thus, it is more appropriate for a Muslim to be in a state of breaking the fast on it. This meaning is supported by his statement (may Allah’s peace and blessings be upon him): “Friday is a day of ʿĪd, so do not make your day of ʿĪd a day of fasting…” And by the statement of ʿAlī (may Allah be pleased with him): “Do not fast on Friday, for it is a day of food, drink, and remembrance.”
There is no inconsistency in the fact that the dislike is lifted by fasting a day before or after it, even though the underlying meaning remains. This is because when Friday is joined to another day of fasting, the added virtue of the combined act of worship compensates for any weakness or shortcoming that might occur in fulfilling the special duties of Friday. Thus, the intended objective is achieved, and the wisdom behind the prohibition is not undermined.
In this there is also an indication of the greatness of Friday’s virtue and its distinguished status—that it is not like the rest of the days.