Sufficient demonstration for the value of fasting that Almighty Allah attributed it to Him. The Messenger of Allah said: '(Allah says) every deed of the son of Adam is for him, except fasting; it is for me and I shall reward for it.

Allah Almighty made fasting a shield for believers from hellfire,  Abu Sa'id al-Khudri reported that Allah's Messenger (PBUH) said: (He who observes fast for a day in the way of Allah He would remove his face from the Hell to the extent of seventy years' distance.)

The prophet (PBUH) wants to save us from hellfire, so he exhorted us to fast three days every month, which is narrated in Bukhari and Muslim that Abu Huraira said: (My intimate friend (the Prophet) advised me to do three things and I shall not leave them till I die, these are: To fast three days every month, to offer the Duha prayer, and to offer witr before sleeping.)

The three days are specified in the narration of At-Tirmidhi, ranked Hasan, Sahih by Al-Albani, that the Messenger of Allah said: "O Abu Dharr! When you fast three days out of a month, then fast the thirteenth, fourteenth, and fifteenth."

Allah Almighty held great reward for fasting these three days, namely it is equal to fasting the whole month. If a Muslim repeated it every month, it would be for him as if he fasted all his life. In this regard, At-Tirmidhi related, ranked sahih by Al-Albani, Abu Dharr narrated: "The Messenger of Allah said: 'Whoever fasts three days in every month, then that is (similar to) fasting every day.' Then Allah Mighty and Sublime is He, attested to that in His Book, by revealing: Whoever brings a good deed, shall have ten times the like thereof. So a day is like ten."

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