There appears in the ḥadīth qudsī the narration; “Every deed of the son of Ādam is for him except fasting; that is certainly for Me and I shall reward for it.” I would like an explanation for this ḥadīth and to know why fasting was specified with this distinction.
Shaykh Ṣāliḥ ibn Fawzān al-Fawzān:
All praise belongs to Allāh ﷻ. This is a great ḥadīth, confirmed on the authority of the Messenger ﷺ who narrates from his Lord who said, “Every deed of the son of Ādam is for him except fasting; that is certainly for Me and I shall reward for it.”1
In this ḥadīth is the virtue of fasting and its merit over all other actions, and that indeed Allāh ﷻ specified it for Himself above the other actions of the servant. And the people of knowledge responded regarding His ﷻ statement: “Fasting is for Me and I will reward for it…” with several answers.
From them were those who said that the meaning of His statement ﷻ “Fasting is for Me and I will reward for it…” is that the actions of the Children of Ādam serves as retribution for what takes place between him and the oppressed. Those oppressed by him will seek retribution on the Day of Judgement by taking something from his actions and good deeds as appears in the ḥadīth, “Indeed a man will come on the Day of Judgment with righteous good deeds the likes of mountains, and he comes whilst having debased this one, and having struck that one, and consumed the wealth of this one. Therefore, this person will take from his good deeds, and that person will take from his good deeds until all of his good deeds have vanished and there remains nothing, then the sins of the oppressed ones will be taken and cast upon him and [as a result] he is cast into the fire.” 2
Except for fasting, for indeed, it is not taken from him to be given to his rivals (from those he oppressed) on the Day of Judgement, rather Allāh ﷻ stores it for the doer and rewards him for it.
And what indicates this is His ﷻ statement, “Every deed of the son of Ādam is for him except fasting; that is certainly for Me and I shall reward for it”, meaning the actions of the Children of Ādam serve as retribution and are taken by his rivals whom he has oppressed on the Day of Judgement, except for fasting, for indeed Allāh ﷻ preserves it and it will not be ruled over by those he oppressed, [but will] remain with Allāh ﷻ for its doer.
And it was said that the meaning of His ﷻ statement, “Fasting is for Me and I will reward for it”, is that fasting is a hidden action nobody knows about except Allāh ﷻ, for it is an intention of the heart in opposition to the rest of the actions which are apparent and seen by the people. As for fasting, it is a concealed action which is between the servant and his Lord ﷻ and for this reason He ﷻ said, “Fasting is for Me and I will reward for it. He indeed abandoned his desires, food and drink for My sake.” And the fact that he abandoned his desires and food for the sake of Allāh, this is a hidden action and a concealed intention that nobody knows about apart from Allāh ﷻ in opposition to charity, for example, and Prayer and Hajj and [other] apparent actions that are seen by the people. As for fasting, nobody sees it, because the meaning of fasting is not merely abandoning food, drink or those things which break the fast, rather alongside this, it must be done sincerely for Allāh ﷻ. And nobody knows this (sincerity of his fasting) except Allāh ﷻ. Thus, His statement, “…He abandoned his desire, food and drink…” etc., is an explanation of His ﷻ statement, “Fasting is for Me and I will reward for it.”
From the scholars are those who said that the meaning of His ﷻ Statement, “fasting is for Me and I will reward for it” is that polytheism does not enter into fasting, contrary to the rest of the deeds which the polytheists present to their objects of worship like: slaughtering, taking oaths and other than that from the different types of worship. Also supplication, fear and hope, for verily many of the polytheists sought nearness to their idols and that which they worshipped with these things in opposition to fasting; it has not been mentioned that the polytheists would fast for their idols and gods. Fasting rather, is specific to Allāh ﷻ and it is upon this that the meaning of His statement, “Fasting is for Me and I will reward for it” is that shirk does not penetrate it, because the polytheists did not seek nearness to their idols with it, but rather fasting is used to seek nearness only to Allāh ﷻ.
1 Refer to Muḥammad ibn Ismāʿīl, Ṣaḥiḥ al-Bukhārī 2/226 of the ḥadīth of Abū Hurairah with that which is similar to it.
2 Refer to Muslim ibn al-Ḥajjāj, Ṣaḥiḥ Muslim 4/100, of the ḥadīth of Abū Hurairah.