Fasting in Arabic is Siyaam.
Linguistically, siyaam means to abstain from something, such as abstaining from speaking. In the shareeah, it is a direct reference to abstaining from food, drink and legal sexual intercourse during the days of the month of Ramadhaan.
The Importance of Siyaam
Fasting is a source of self-restraint, piety and God-consciousness. It was prescribed by Allah for the prophets before Prophet Muhammad (peace be upon him). In the verses obligating the fast of the month of Ramadhaan, Allah has pointed out its goal or purpose:
"O you who have believed, decreed upon you is fasting as it was decreed upon those before you that you may become righteous [self-restraint, piety and God-consciousness]".
The Prophet (peace be upon him) said that fasting is a protection from the Hell-fire:
"Fasting is a shield from the Hell-fire like one of your shields shielding you while fighting."
Furthermore, it will also come as an intercessor on the Day of Judgment. The Prophet (peace be upon him) has said,
"The fast and the Quran shall come as intercessors on the Day of Resurrection. The fast shall say, 'O Lord, I prevented him from his food and drink during the day, so let me intercede for him. ' The Quran will say, 'I kept him from sleep during the night, so let me intercede for him. ‘Then they will be allowed to intercede."
It is an act that demonstrates one’s sincerity to Allah. Only Allah is aware if a person truly fasted or not. No one can know if he secretly broke his fast. Therefore, Allah has a special reward for those who fast. This is stated in the following hadith qudsi, Allah has said,
"He leaves his food, drink and desires because of Me. Fasting is for My sake and I shall reward it. And every good deed shall be rewarded tenfold."
The Prophet (peace be upon him) said,
"Whoever fasts the month of Ramadhaan with faith and hoping for its reward shall have all of his previous sins forgiven for him."
Also important to note that the Prophet (peace be upon him) said,
"While I was sleeping, two men came to me and took hold of my arms. They brought me to a steep mountain and said, 'Climb.' I said, 'I am not able to.' They said, 'We will make it easy for you. ' So I climbed until I came to the summit of the mountain where I heard terrible cries. I said, 'What are these cries?' They said, 'Those are the cries of the inhabitants of the Fire. ' Then they took me further until I came to a people who were strung up by their hamstrings, and their jawbones were tom and flowing with blood. I said, 'Who are these people?' He said, 'Those are the people who break their fast before the time it was permissible to do so. "'