abu hurairah narrated; "allah's messenger (peace be upon him) said; 'when the month of ramadan starts, the gates of jannah (paradise) are opened and the gates of jahannam (hell) are closed, and the shayatin (devils) are chained up."
the gates of jannah (paradise) are opened in this month because a great deal of righteous deeds are performed, and as an encouragement for those who seek allah's reward. while the gates of jahannam (hell) are closed because only a few sins are committed by the believers. the shayatin (devils) will be chained that they may not have the influence on the believers by whispering to them and misguiding them, that they might ordinarily have during the other months of the year.
allah has prescribed fasting and made it obligatory on all nations. he has said;
"o you who have believed, decreed upon you is fasting as it was decreed upon those before you that you may become righteous"
[noble quran 2:183]
if fasting were not a great act of worship, and the reward thereof were not so great allah would not have prescribed it on all nations.
of the virtues of fasting is that it is a means for atonement of sins. it is narrated on the authority of abu hurairah that;
"the prophet (peace be upon him) said; "allah has said; 'all the deeds of adam's children (all mankind) they do for themselves, except fasting which belongs to me and i will reward for it. fasting is a shield (against the hell and against the committing of sins). if one of you happens to be fasting he should avoid sexual relations with his wife and should avoid quarrelling. should someone fight or quarrel with him, let him say, 'i am fasting'. by him in whose hand is my soul (allah), the smell of the mouth of the one who is fasting is better in the sight of allah than musk (perfume)."
[from the collection of sayings of the prophet by imam bukhari]
it is a shield because it safeguards the believer from vain talk and wrong doing and thereby protects him from the jahannam (hell).
of all the good deeds, allah has favored fasting to be greatly rewarded by him and distinguished it with prestige, if it is observed with the pure intention of pleasing him alone.
from other sayings of the prophet (peace be upon him) we know that:
fasting is so highly regarded for a believer that he would have two occasions of joy, one at the time of breaking his fast, [to enjoy the bounties of allah, because he has been favored with allah's mercy to observe fasting while many others have been deprived of this great blessing], and the second would be when he meets his lord [and enjoys the abundant reward for having observed fasting].
also, that fasting intercedes with allah on behalf other believer on the day of judgment.
taken from "virtues of ramadan" by sheik muhammad bin utheimin
translated by abdullah al-farsi - series on islam #17
prepared by yusuf estes