Abu Hurairah relates that the Holy Messenger (peace and blessings of Allah be to him) said, “The reward of each good act may be ten to seven hundred times, but the reward of fasting is an exception as God says, ‘Fasting is for My sake and I will reward for it as much as I like.’ A fasting man gives up food and drink for His sake. He will have two great joys: one, at the time of breaking fast; and the other on meeting his Lord. Smell of the fasting person’s mouth is better than that of musk before God and fasting is a shield against evil. A fasting man should not indulge in obscene talk or noisy demonstrations or rioting. If anyone abuses him, he should excuse himself from retaliation saying that he is fasting.”
(Bukhari, Muslim)
Allah rewards each good act ten to seven hundred times but keeps the reward of fasting due to Himself. For, fasting is known only to God and the person who fasts. A fasting person has two great joys: the joy of breaking the fast, and the joy of meeting the Lord.
Fast is a shield providing power to defend oneself against the assaults of Satan. If the spirit of fast is fully observed, viz. the mind, heart and tongue join in the fast, it will become evident how fast becomes a shield against sins. Even if someone drags a fasting person to sinful acts or abuse or brawl, he should excuse himself by simply saying that he is fasting.