The translations of the two hadiths regarding the issue are as follows: "Fasting is a shield (or a screen or a shelter). So, the person observing fasting should not behave foolishly and impudently, and if somebody fights with him or abuses him, he should tell him twice, 'I am fasting. By Him in Whose Hands my soul is, the smell coming out from the mouth of a fasting person is better in the sight of Allah than the smell of musk. (Allah says about the fasting person), 'He has left his food, drink and desires for My sake. The fast is for Me. So I will reward (the fasting person) for it and the reward of good deeds is multiplied ten times."(Bukhari, Sawm, 2).Allah says, "All the deeds of Adam's sons (people) are for them, except fasting which is for Me, and I will give the reward for it.”Fasting is a shield or protection from the fire and from committing sins. If one of you is fasting, he should not utter bad words and quarrel. If somebody should fight or quarrel with him, he should say, 'I am fasting.'By Him in Whose Hands my soul is' The unpleasant smell coming out from the mouth of a fasting person is better in the sight of Allah than the smell of musk. There are two pleasures for the fasting person, one at the time of breaking his fast, and the other at the time when he will meet his Lord." (Bukhari, Sawm 9; Muslim, Siyam 163)The meaning of the sentence in the hadith, “All the deeds of Adam's sons (people) are for them, except fasting which is for Me” is as follows:All of the other deeds and worship generally have some aspects that are related to outward appearance; so, there may be hypocrisy or show off in them. However, fasting is worship that is based on intention and related to the heart. Hypocrisy or show off is not in question in fasting because it has no aspects related to outward appearance. A person may eat at home and act as if he is fasting outside. Therefore, if a person fasts, it means he fasts for Allah.
Since fasting is a sincere act of worship based on the consent of Allah, its reward will be special; the criterion “ten or more rewards for one deed” will not be applied for fasting; it will have a criterion unlike and beyond the other criteria and it will be presented like a divine surprise. (see Ibn Hajar, the explanation of the relevant verse)
That is the meaning of “fasting being a kind of worship done only for the sake of Allah” means a kind of worship that is free from hypocrisy and show off that cannot be known by others unless the person fasting mentions it. For, fasting does not have an aspect that can be seen and understood from the outside.
On the other hand, the polytheists in history did not have any kind of worship for their idols similar to fasting. That is, no idolater worshipped idols by fasting. In this sense, fasting is a kind of worship performed only for Allah.
Another different aspect of worship from other worship is that its reward will be determined by Allah - in a way superior to the criteria declared before.
Both properties are enough for us to understand the virtue and superiority of fasting.
The hadith states and declares that the reward to be given for fasting is beyond and superior to the criterion of ten to seven hundred times for one good deed and that it will be determined by Allah, indicating the exceptional place of fasting and its virtue in our religion. The virtue of fasting originates from the fact that our Lord said, "Fasting is for me" and "I will give the reward for it", opening the door of endless grace and generosity to the person who fasts. Such honoring and compliments are superior to anything. It forms the glad tiding in the hadith.
"All the deeds of Adam's sons are for them." The reason why the sentence above is stated by Allah is that all of the worship except fasting has an aspect that man takes pleasure from, that he cannot hide from others and that he might want to show. That fasting does not have these properties shows how sincere and special worship it is. This is the main determination regarding the hadith in the question.
- The only worship about which Allah says, " I will give the reward for it" is fasting.
- No sacrifice and deed done for Allah remains without reward.
- A person who fasts means a person wearing a shield against sins and torture in Hell. For, the Prophet said,"Fasting is a shield."