What are the white days, and why are they fasted?

What the white days are

The white days (al-ayyam al-bid) are the three middle days of every lunar month. Shaykh Ibn Baz defined them plainly: they are the 13th, 14th and 15th — the days whose night is white with moonlight and whose day is white with the sun.

A small number of scholars held a different set of dates, and Ibn Rushlan reports a rare view that the 12th replaces the 15th. The correct position, as Ibn Uthaymeen and al-Shanqiti both state, is the first: 13, 14 and 15. Ibn Rushlan notes that the language itself supports this, since the nights of the 13th, 14th and 15th are the ones called "white."

One point of language worth keeping: the description properly belongs to the nights, not the days. Ibn Barri said the correct phrase is "the days of the white nights" — since it is the nights that turn white with the moon. The common usage "the white days" is how the hadith and most jurists express it.

Why they are fasted

The fast of these days rests on a clear instruction from the Prophet ﷺ. Abu Dharr رضي الله عنه narrated:

"If you fast three days of the month, then fast the thirteenth, fourteenth and fifteenth."— Sunan al-Tirmidhi 761, from Abu Dharr

Qatadah ibn Milhan reported something similar, and added that the Prophet ﷺ described these days as being "like the whole age" — meaning the reward equals a lifetime of fasting, because each good deed is multiplied tenfold. Three days counted as thirty, and so on through the year.

The scholars give two reasons for the choice of these particular days:

• The reward of a lifetime: three days a month, multiplied tenfold, equals fasting the entire year. This is the primary reason, drawn directly from the hadith.
• A physical wisdom: Ibn Uthaymeen and al-Shanqiti both mention that scholars of medicine observed the blood surges and sleep is disturbed in these nights when the moonlight is fullest. Fasting lightens the body's burden at that time. Ibn Uthaymeen adds an important caution: bodily benefits should never be the reason we worship — they are a secondary mercy, not the goal. The goal is drawing near to Allah.

The ruling and its rank

Fasting the white days is mustahabb — recommended, not obligatory. Ibn Uthaymeen explains the term precisely: a recommended act is one for which the doer is rewarded if he acts in obedience, and the one who leaves it is not punished. It ranks below the obligatory acts in Allah's love, as the hadith qudsi states: "My servant does not draw near to Me with anything more beloved to Me than what I have made obligatory upon him."

The scholars agree that fasting three days of each month is a sunnah. The disagreement is only over which three days are best:

Al-Shanqiti notes that Imam Malik's position likely arose because the hadith had not reached him, and that it is reported he later fasted them himself. The correct and stronger view, he concludes, is that fasting the white days is a recommended act of worship and not prohibited.

If you miss the white days

The month is not restricted to those three days. Ibn Baz explains that the whole month is a place for this fast — if you fast three days at the beginning, middle or end, you have fulfilled the sunnah, though the white days are better. He adds that if you habitually fast the white days and are then prevented, you may make them up elsewhere in the month, and this is not technically a "make-up" (qada), because the entire month is open for it.

Ibn Uthaymeen draws a fine distinction: if you fast three days outside the white days, you earn the reward of fasting three days of the month — not specifically the reward of the white days — and you still attain the reward of fasting a lifetime.

How to know when they fall

Ibn Baz advises fasting them according to the calendar, acting on the predominant assumption, since most people cannot sight the moon themselves. The month is established by sighting the crescent or by completing the previous month at thirty days. If the calendar is slightly off and you fast on the wrong days, Ibn Baz notes that it still suffices, because the Prophet ﷺ encouraged three days of the month without restricting them to the white days.

You may fast them consecutively or separately — the hadiths are unrestricted on this point.

Key takeaways

• The white days are the 13th, 14th and 15th of each Hijri month, named for the moonlit whiteness of their nights.
• Fasting them is a confirmed sunnah, not an obligation — rewarded if done, no sin if left.
• The reward equals fasting a lifetime, because three days multiplied tenfold covers the month, and so the year.
• If you miss them, fast any three days of the month — the sunnah is fulfilled, though the white days are more virtuous.
• Follow the calendar to determine the dates, since sighting the moon is not practical for most people.

Further reading

• Ibn Uthaymeen, al-Sharh al-Mumti' 'ala Zad al-Mustaqni' — the chapter on voluntary fasting
• Ibn Taymiyyah, Sharh 'Umdat al-Fiqh — the section on the white days
• Ibn Baz, Majmu' al-Fatawa — the chapters on voluntary fasting

And Allah knows best.