Sunnah Fasting Days: A Complete Guide to Voluntary Fasting in Islam

What is Sunnah (Voluntary) Fasting?

In Islam, fasting (Sawm) is not limited to the obligatory fasting of Ramadan. The Prophet Muhammad (peace be upon him) regularly fasted on specific days throughout the year, and these voluntary fasts — known as Sunnah fasting — carry great spiritual rewards for those who observe them.

Sunnah fasting differs from Ramadan fasting in several important ways: it is voluntary (not obligatory), the intention (niyyah) can be made during the morning before noon if one has not yet eaten, and it can be broken without consequence. The reward, however, is genuine and significant, with the Prophet describing the benefits of specific voluntary fasts in numerous authentic Hadith.

Monday and Thursday Fasting

Fasting on Mondays and Thursdays is among the most frequently recommended voluntary fasts. When asked about his fasting on these days, the Prophet (peace be upon him) explained:

"Deeds are presented (to Allah) on Monday and Thursday. I love for my deeds to be presented while I am fasting." (Tirmidhi)

In another narration, the Prophet said that it was also on Monday that he was born and on Monday that revelation first came to him, adding another layer of significance to this day.

How to Observe

• Make the intention to fast before Fajr, or even before noon if you have not yet eaten or drunk anything that day
• Abstain from food and drink from Fajr until Maghrib
• Break the fast at Maghrib time, ideally with dates and water, following the Sunnah

The Three White Days (Ayyam al-Bid)

The Prophet (peace be upon him) is reported to have recommended fasting on the 13th, 14th, and 15th of each Islamic lunar month. These days are called the "White Days" (Ayyam al-Bid) because the full moon is at its brightest during these nights, illuminating them with white light.

The Prophet said: "Fasting three days of each month is like fasting the whole year." (Bukhari and Muslim)

This is because good deeds are multiplied tenfold: 3 days × 10 = 30 days (equivalent to the full month), and 12 months × 3 days = 36 days of fasting, which equals the reward of an entire year.

How to Observe

• Observe on the 13th, 14th, and 15th of each Hijri month
• Note that on the 13th of Dhul Hijjah, this falls during the Tashreeq days when fasting is generally prohibited for non-pilgrims in some scholarly opinions — consult your local scholars
• Use the Hijri Guide calendar to track which Gregorian dates correspond to the 13th, 14th, and 15th of each month

Six Days of Shawwal

Among the most widely practiced Sunnah fasts is the fasting of six days in the month of Shawwal — the month immediately following Ramadan. The Prophet (peace be upon him) said:

"Whoever fasts Ramadan and follows it with six days of Shawwal, it is as if he fasted for a lifetime." (Muslim)

The calculation is similar to the White Days: 30 days of Ramadan + 6 days of Shawwal = 36 days. Multiplied by 10 (the minimum multiplication of good deeds) = 360 days, which is approximately equivalent to a full lunar year.

How to Observe

• Begin after Eid al-Fitr (not on Eid day itself, as fasting on Eid is prohibited)
• The six days do not need to be consecutive — you can spread them throughout Shawwal
• Make up any missed Ramadan fasts first before beginning Shawwal fasts, according to some scholars' opinions (though this is a point of scholarly difference)
• The six days of Shawwal are one of the best investments of time in the Islamic year

Fasting on the Day of Arafah (9th Dhul Hijjah)

The Day of Arafah is the most important day of Hajj — the day pilgrims stand at the Plain of Arafah in prayer. For Muslims who are not performing Hajj, fasting on this day carries extraordinary reward.

The Prophet (peace be upon him) said: "Fasting on the Day of Arafah expiates the sins of the previous year and the coming year." (Muslim)

This is one of the most powerful voluntary fasts in Islam, as it expiates two years' worth of minor sins in a single day.

Important Note

Those who are performing Hajj do not fast on the Day of Arafah, as they need their full strength and energy to complete the Hajj rituals. The fast is recommended specifically for those not on pilgrimage.

Fasting on Ashura (10th Muharram)

The 10th of Muharram, known as Ashura, is one of the most significant days for voluntary fasting in Islam. When the Prophet arrived in Medina, he found the Jewish community fasting on this day. He asked about it and was told they fasted because Allah saved Prophet Musa (Moses) and the Children of Israel from Pharaoh on this day. The Prophet said: "We have more right to Musa than they do," and he fasted on that day and instructed his companions to fast as well.

The Prophet also said: "Fasting on the day of Ashura, I hope Allah will accept it as expiation for the year before it." (Muslim)

Fasting on the 9th as well

The Prophet intended to distinguish the Muslim Ashura fast from the Jewish one by also fasting the day before (9th Muharram) or the day after (11th Muharram). He said: "If I live until next year, I will certainly fast the ninth as well." (Muslim) It is therefore Sunnah to fast on both the 9th and 10th of Muharram (or 10th and 11th).

Fasting in the Month of Sha'ban

The month of Sha'ban — the month immediately before Ramadan — was the Prophet's favorite month for voluntary fasting. Aisha (may Allah be pleased with her) reported: "I never saw the Prophet fast an entire month except for Ramadan, and I never saw him fast more in any month than he did in Sha'ban." (Bukhari and Muslim)

The Prophet explained: "That is a month people neglect, between Rajab and Ramadan. It is a month in which deeds are raised to the Lord of the Worlds, and I love for my deeds to be raised while I am fasting." (Nasai)

Note on Fasting in the Last Days of Sha'ban

Most scholars recommend stopping voluntary fasting a few days before Ramadan begins (usually after the 15th of Sha'ban) to ensure you enter Ramadan with energy and readiness. Fasting on the 30th of Sha'ban specifically to "get a head start" on Ramadan is discouraged.

The Month of Muharram

Beyond Ashura, the entire month of Muharram — the first month of the Islamic year and one of the four sacred months — is recommended for increased voluntary fasting. The Prophet said: "The best fasting after Ramadan is the fasting of the month of Allah, Muharram." (Muslim)

Scholars note that while the Prophet recommended fasting in Muharram, he himself fasted most in Sha'ban, which shows that fasting any amount in Muharram is blessed, not necessarily the entire month.

Fasting During the Sacred Months

The four sacred months in Islam — Muharram, Rajab, Dhul Qi'dah, and Dhul Hijjah — are periods of special sanctity during which good deeds carry extra weight. While specific Sunnah fasts within these months (like Ashura in Muharram and Arafah in Dhul Hijjah) are explicitly recommended, voluntary fasting during any of the sacred months is considered praiseworthy.

Practical Tips for Sunnah Fasting

• Start with one day: If you're new to voluntary fasting, begin with Monday fasting or the 9th and 10th of Muharram. Don't overwhelm yourself.
• Make the intention: Even if you wake up and decide to fast before noon (having not eaten or drunk), a voluntary fast is valid. The intention does not need to be made the night before, unlike Ramadan.
• Break the fast if needed: Unlike Ramadan, you can break a voluntary fast without sin or needing to make it up, though it is better to complete it.
• Track the Islamic calendar: Use Hijri Guide to track the Islamic calendar dates so you always know when the 13th-15th of each month are, when Ashura falls, and when the Day of Arafah is.
• Combine intentions: If Monday happens to be the 14th (White Day), you can fast with the intention of both, getting the reward for both types of Sunnah fasting.
• Be consistent: The Prophet loved consistent deeds, even if small. The Prophet said: "The most beloved deeds to Allah are those done consistently, even if they are small." (Bukhari)

Conclusion

Sunnah fasting is one of the most accessible and rewarding forms of extra worship in Islam. Whether you fast every Monday and Thursday, observe the White Days, or make the most of the six days of Shawwal after Ramadan, these voluntary fasts provide a means of drawing closer to Allah, expiating sins, and building the spiritual discipline that makes Ramadan even more meaningful.

Use the Hijri Guide Islamic calendar to plan your voluntary fasts throughout the year and ensure you never miss these spiritually rich opportunities.