[Commentary]
In this chapter the author—may Allah have mercy on him—explains the days and months for which fasting is recommended. Among them are:

1. Fasting in Shaʿbān. The Prophet (peace and blessings be upon him) would fast the whole of Shaʿbān, or all of it save a few days, as ʿĀʾishah (may Allah be pleased with her) reported. For that reason a Muslim should fast frequently during Shaʿbān, even more than in other months, because the Prophet ﷺ did so.

   The scholars say the wisdom behind this is that Shaʿbān comes before Ramadan the way the regular sunnah prayers precede the obligatory prayer.

2. Fasting Allah’s month Muḥarram—the interval between Dhū al-Ḥijjah and Ṣafar. Concerning it the Prophet ﷺ said, “The most virtuous fast after Ramadan is Allah’s month Muḥarram.” It is especially emphasized to fast the ninth, the tenth, and the eleventh days.

3. Fasting three days of every month, as in the hadith of the Bāhilī. The Prophet ﷺ used to fast three days each month and did not mind whether they were at the beginning, middle, or end of the month. Still, the “white days” are preferable: the thirteenth, fourteenth, and fifteenth.

4. Fasting on the Day of ʿArafah, for when the Prophet ﷺ was asked about that fast he said, “It expiates the sins of the preceding year and the coming year,” meaning it is an atonement for two years.