The virtues of fasting are great indeed, and one of the things reported in the saheeh ahaadeeth is that Allaah has chosen fasting for Himself, and He will reward it and multiply the reward without measure, as He says [in the hadeeth qudsi]:
"Except for fasting which is only for My sake, and I will reward him for it." (al-Bukhaari, al-Fath, no. 1904; Saheeh al-Targheeb, 1/407).
Fasting has no equal (al-Nisaa'i, 4/165; Saheeh al-Targheeb, 1/413), and the du’aa’ of the fasting person will not be refused (reported by al-Bayhaqi, 3/345; al-Silsilat al-Saheeh, 1797).
The fasting person has two moments of joy: one when he breaks his fast and one when he meets his Lord and rejoices over his fasting (reported by Muslim, 2/807).
Fasting will intercede for a person on the Day of Judgement, and will say, "O Lord, I prevented him from his food and physical desires during the day, so let me intercede for him." (Reported by Ahmad, 2/174. Al-Haythami classed its isnaad as hasan in al-Majma’, 3/181. See also Saheeh al-Targheeb, 1/411).
The smell that comes from the mouth of a fasting person is better with Allaah than the scent of musk. (Muslim, 2/807).
Fasting is a protection and a strong fortress that keeps a person safe from the Fire. (Reported by Ahmad, 2/402; Saheeh al-Targheeb, 1/411; Saheeh al-Jaami’, 3880).
Whoever fasts one day for the sake of Allaah, Allaah will remove his face seventy years’ distance from the Fire. (Reported by Muslim, 2/808).
Whoever fasts one day seeking the pleasure of Allaah, if that is the last day of his life, he will enter Paradise. (Reported by Ahmad, 5/391; Saheeh al-Targheeb, 1/412).
"In Paradise there is a gate called al-Rayyaan, through those who fast will enter, and no one will enter it except them; when they have entered it will be locked, and no-one else will enter through it." (al-Bukhaari, Fath, no. 1797).
Ramadaan is a pillar of Islam; the Qur’aan was revealed in this month, and in it there is a night that is better than a thousand months.
"When Ramadaan begins, the gates of Paradise are opened and the gates of Hell are closed, and the devils are put in chains." (Reported by al-Bukhaari, al-Fath, no. 3277).
Fasting Ramadaan is equivalent to fasting ten months (See Musnad Ahmad, 5/280; Saheeh al-Targheeb, 1/421).
"Whoever fasts Ramadaan out of faith and with the hope of reward, all his previous sins will be forgiven." (Reported by al-Bukhaari, Fath, no. 37).
At the breaking of every fast, Allaah will choose people to free from Hellfire. (Reported by Ahmad, 5/256; Saheeh al-Targheeb, 1/419).