Why Observe the Inward Aspects of Fasting?- Imam Ghazali

Importance of Observing Inward Aspects

Now you may say:  'Suppose someone confines himself  to
curbing his appetite for food and drink and his sexual desire,
to  the  neglect  of  the inward aspects.  According  to  the 
experts in jurisprudence (Fiqh) his Fast (Saum) is valid.
So what are we to make of this?' 

You must realise that the scholars of external legality are 
concerned only with such obligations as fall within the capac- 
ity of ordinary heedless people, wholly caught up in the affairs 
of this world.
As for those learned  in  knowledge of  the Hereafter, the 
meaning they attach to validity is acceptance, and by  accept- 
ance they mean attainment  of  the goal. According to their
understanding, the goal of Fasting is the acquisition of one of
the qualities of God, Great and Glorious is He, namely stead-
fastness (samadiya), as well as following the example of  the
angels by  abstaining as far as possible from the desires of the
flesh, for they are immune to such passions. The human status
is superior to that of the animals, since man is able by the light
of reason to tame his lust; yet it is inferior to that of the angels,
in that he is subject to carnality and put to the test in combat
with its temptations.
Whenever man falls prey to lust, he sinks to the lowest of
the low and joins  the animal herd. Whenever he curbs his
desires, he ascends to the highest of  the high and attains the
angelic level. The angels are near the presence of God, Great
and Glorious is He, so those who follow their example and
model themselves on their character will likewise draw near to
God, Great and Glorious is He. To resemble one who is near
is  to  be  near.  This nearness, however,  is  not spatial but
qualitative.
If  this  is  the  secret  of  Fasting among men  of  profound
spiritual understanding,  what benefit is  to be derived from 
postponing a meal only to combine two meals after sunset, 
while indulging in all other passions the whole day long? If
there were any good in such conduct, what could the Prophet,
on him be peace, have meant by saying: 'How many of those
who Fast get nothing from it but hunger and thirst?' (Nasai
& Ibn Majah).
This is why Abul Darda' said: 'How fine is the sleep of the
wise and their non-Fasting! Don't they just  put to shame the
Fasting and wakefulness of fools! A mere atom from those
possessed of  certainty and true piety is better and weightier
than seeming mountains  of  worship by  the misguided.'  For
the same reason one of the scholars said: 'How many who Fast
are not keeping Fast, and how many who do not keep Fast are
Fasting!'
The Fasting non-Faster  is  he  who  keeps  his  limbs  and
organs pure of  sin while still  eating and drinking; the non-
Fasting Faster is he who goes hungry and thirsty while giving
full licence to his limbs and organs. Those who understand the
significance of Fasting and its secret meaning are aware that
he  who  abstains from  food,  drink  and sexual intercourse,
while breaking Fast by involving himself in sin, is like one who
performs his ablution by wiping part of  his body three times
(in  compliance  with  the external  legal  requirement),  yet
neglects what is really important, namely the actual washing.
Because  of  this  stupidity  his ritual Prayer  is  rejected.  By
contrast, he who does not abstain from eating, yet does Fast in
the sense of keeping his organs Free from all that is unworthy,
is comparable to one who washes the proper parts of his body
only once each. God willing, his ritual Prayer is acceptable,
since he has paid due attention to the essentials, even if he has
omitted the details. But he who  combines the two may  be
compared to one who not only washes each part of the body,
but does so three times each, for he attends to essentials and
details alike, and this constitutes perfection.
The Prophet, on him  be peace, once said: 'The Fast is a
trust, so let each of you keep this trust!" (Kharaiti; Hasan)
 And when he recited the words of God, Great and Glorious is He: 
'Surely  God  bids  you  restore  trusts  to their  owners.'
[al-Nisa', 4: 58]
 he touched his ears and his eyes, saying: 'Hearing is a trust and 
sight is a trust.' (Abu Dawud) If speech were not likewise a trust
of the Fast, the Prophet, on him be peace, would not have said:
'Say:  "I  am Fasting!"' (Bukhari & Muslim).
 In other words: 'My  tongue has been entrusted to 
my care, so how can I release it to answer your insults?'
It therefore becomes apparent that every act of worship has
both an outer and an inner aspect, a husk and a kernel.