Literally the word “SOUM” means to “hold on” “stop”, “refrain from”.

In religious terminology it means to refrain from eating, drinking and inter course.
(Surah: Baqarah, Verse: 187)

Note: Sayaam is the plural of Soum.

FARZ SAYAAM: THE OBLIGATORY FASTING:

Fasting in the month of Ramadan is “FARZ” obligatory and binding; so who so ever, happens to be in the month of Ramadan, ought to observe fasting.
(Surah: Baqarah, Verse: 185)

VIRTUES AND BLESSINGS OF RAMADAN:

As the month of Ramadan arrives the doors of paradise, heavens and blessings are made open, while the doors of hell are shut and closed, and the disobedient and rebellious Shaitans are chained.
(Saheeh Muslim)

Ramadan is a month of blessings, and this is the month in which the holy Quran was revealed and alighted. And there is the night in this month, which is of great excellence, eminence, grandeur, peace and blessings. And this is the night more virtuous, blessed and blissful than thousand months.
(Surah: Baqarah, Verse: 185)

During this month, every night, a proclaimer gives a call, like this. O, the seeker of virtues be blessed, and the seeker of evil refrain from doing so. This is the month during which every night the Almighty Allah sets at liberty a large number of people from hell.
(Tirmizi, Kitab-us-Soum, Sanad: Saheeh)

VIRTUES AND BLESSINGS OF SOUM (FASTING):

The Soum (fasting) is like a protecting shield. The odour coming from the mouth of the fasting man is better than the fragrance of musk for Allah. The Soum is purely and exclusively for Allah, and He alone will give its reward.
(Saheeh Bukhari)

In paradise, there is a door known as the “RAIYYAN”, through which only the fasting ones will enter, none else.
(Saheeh Bukhari)

For every virtue, there is a reward, ranging from 10 to 700 times, except the Soum (Fasting) How much is the requital for Soum ? Only Allah knows the requital for Soum (fasting).
(Saheeh Bukhari, Saheeh Muslim)

There are two joyous moments for the (Saim) the fasting man, one when he breaks the fast, and the second, when he will have an audience with his Creator, the Supreme Lord.
(Saheeh Bukhari, Saheeh Muslim)

One who observed a fast for one day, for the sake of Allah, then Allah on account of that fast will keep him (his face) away from hell at a distance equivalent to a traveling of seventy (70) years.
(Saheeh Muslim)