What is the Reason Behind Fasting 3 Days a Month?

Question: Assalamu Alaikum, I used to fast the white days but today as I was fasting I see that I have started my fast on the wrong date which is 2 in white days and 1 day out so what is the reason behind fasting in 3days.

Even though you were unable to fast the 13th, 14th, and 15th you still fulfilled the Sunna of fasting three days.

This is because there are two separate Prophetic practices (Sunan pl. of Sunna) regarding voluntary fasts throughout the month. One Sunna is to fast three days a month. The other is to specifically fast the 13th, 14th, and 15th of the lunar month, as the three days. This can be seen from the following Hadith:

Mua’dh said, “I asked Aisha (may Allah be pleased with her), “Did the Messenger of Allah used to fast three days every month?” She replied, “Yes.” I said, “Which part (of the month) did He fast?” She said, “He didn’t pay any mind as to which (days) He fasted.” [Tirmidhi]

The General Sunna of Fasting Three Days a Month

The Messenger of Allah (may Allah bless him and give him peace) said, “Whoever fasts three days of each month, then that is the lifelong fasting. For Allah, Exalted and Majestic, has sent down verification to that in His book: (Whoever brings a good deed, for them is ten the like of it…) [Qur’an; 06:160] So one day is equal to ten.” [Tirmidhi]

The Specific Sunna of Fasting the Three Bright Days

The Messenger of Allah (may Allah bless him and give him peace) said, “O Abu Dharr, If you fast, of the month, three days, then fast the 13th, 14th, and 15th.” [Tirmidhi]

May Allah increase you in your desire to follow the Prophetic Way.
Allahu A’alam

[Shaykh] Yusuf Weltch

Checked and Approved by Shaykh Faraz Rabbani

Shaykh Yusuf Weltch is a graduate from Tarim; a student of Habib Umar and other luminaries; and authorized teachers of the Qur’an and the Islamic sciences.