There are some Existence (like Invisible Master)/worship (same as fasting)/situation like (Virginity of a Woman) that, exist in human life about which evidence can not be given to another person but only the person involved knows that it is truth. Fasting means a man will not take any food, water, etc, or any form of food, drink & abstain from works prohibited by his religious law during certain time period in a day. He can not give a proof or evidence to another person about above situation of his life. Only GOD & the person involve knows that he did not take any form of food or water during certain time period. This is a form of training about voluntarily accepting sufferings which can be applied in other field of practical life like not to speak lie, not to take profit or enjoy life at the cost of others loss or sufferings. Also this type of worship is an example of giving evidence to a non believer about believes in the existence of an invisible Master Who is Omniscient & the Creator of Universe.
Following verses about fasting are represented below from Holy Scriptures:
Sura 2/183 Believers, fasting has been prescribed for those before you, so that you
may guard yourselves against evil.(Deuteronomy 9/9, Mathew 4/2 )
Sura 2/184 Fast for a specific number of days, but if any one among you is ill or on a journey, let him fast the same number of days latter. For those who can fast with extreme difficulty, there is a way to compensate- the feeding of a needy person. But he who does good of his own accord shall be well rewarded : but to fast is better for you, if you only know. Sura 2/185 The month of Ramadan is the month when Quran was sent down as guidance for mankind with clear proof of guidance and the criterion by which to distinguish right from wrong. Therefore whoever of you is present in that month, let him fast. Sura 2/187 Eat & drink until the white thread of dawn becomes distinct from black, then resume the fast until nightfall.
Verses from New Testament (NIV Bible) about fasting
Mathew 4/2 After fasting forty days & forty nights, he (Jesus) was hungry.
Mathew 5/6 Blessed are those who hunger & thirst for righteousness (Fasting), for
they will be shown mercy.(Jesus told)
Verses from Old Testament (NIV Bible) about fasting
Deuteronomy 9/9 – I (Moses) stayed on mountain forty days & forty nights. I ate no
bread & no water, Deuteronomy 9/18
From the examination of above verses it is clear that prophet Moses (pbu), prophet Jesus (pbu) & last prophet Muhammad (pbu) observed fasting during their life time. so
It is an obligatory duty for the descendant of Abraham to observe fasting ,
mentioned in the above verses from Sun rise to Sun set during the month of Ramadan.
In Holy Quran it has been instructed to observe fasting in the month of Ramadan (ninth
lunar month) as it started to descend in the month of Ramadan (sura 2/185).
If solar month like (December/January) would have been set for fasting, then people of
Northern hemisphere would observe fasting in winter throughout the life which would
Have been comfortable for them, but people in southern hemisphere would observe
fasting in summer (December/January) throughout the life which would have been uncomfortable for them.
But if lunar calendar is followed then the people of Northern hemisphere
will get this fasting month in both summer & winter in their life time. Same is true
for the people of southern hemisphere means fasting month in both summer & winter
in their life. This happens due to the situation that, every year ten days shift
backward in case of lunar calendar which result the appearance of same month in
both summer & winter after several years in all the parts of the world. So following
fasting month according to lunar calendar makes equal favor to men in all the parts of
the Globe. Holy Quran came to this world in six hundred century &
countries of southern hemisphere like Australia was discovered in 1788 century . Brazil was discovered after 1400 century, so it was not known
at that time that , when countries of north hemisphere face winter, then
countries of south hemisphere face summer. As the Last prophet was the prophet
for whole world (Sura 7/158) , so fasting law was set in such a way that it makes equal
favor to the people living in all the parts of the world, which means it was an order
from GOD Almighty Who knows every things but not a choice of last prophet.