The reward for fasting is immense, as mentioned in the following Hadeeth: “Every action of the son of Adam is given manifold reward, each good deed receiving ten times its like, up to seven hundred times. Allah the Most High said, ‘Except for fasting, for it is for Me and I will give recompense for it, he leaves off his desires and his food for Me.’ for the fasting person there are two times of joy; a time when he breaks his fast and a time of joy when he meets his Lord, and the smell coming from the mouth of the fasting person is better with Allah than the smell of musk.” [al-Bukhaaree]
Also, Sahl ibn Sa’ said that the Prophet (s.a.w.) said: “Indeed there is a gate of Paradise called ar-Rayyaan. On the day of Resurrection those who fast will enter through it; no one enters it except for them, and when they have entered, it is closed so that no one enters it, so when the last of them enters it, it is closed, and whoever enters it drinks, and whoever drinks never becomes thirsty.” [Ibn Khuzaimah, Saheeh].
Fasting is a shield against the Fire: “Fasting is a shield with which a servant protects himself from the Fire.” [Ahmad, Saheeh] and his saying (saws) “No servant fasts on a day in the path of Allah except that Allah removes the hellfire seventy years further from his face.” [related by the group except for Abu Dawood]
On the Day of Judgement, “Fasting will say: O My Lord I prevented him from food and desires so accept my intercession for him.” [Ahmad, al-Haakim and Abu Nu’aim, Hasan]
Fasting is a means for one’s sins to be forgiven. The Prophet (s.a.w.) said: “He who fasts Ramadhan, due to Iman and hoping for reward (from Allah) then his past sins are forgiven.” [al-Bukhaaree, Muslim]
Fasting is an expiation for various sins, as mentioned in the Qur’aan, in verses: 2:196, 4:92, 5:89, 5:95 and 58:3-4.