Multiplication of Good Deeds
In Ramadhan especially, the reward of every good deed is multiplied. But did you know that the type of multiplication for fasting is not the same as other good deeds? This is one of the IMMENSE rewards from Allah to those who fast. Rasulallah s.a.w. said that Allah s.w.t. said:
“Every act of the son of Adam is for him,
except As-Siyam (fasting) which is (exclusively) for Me,
and I will reward him for it…” 
Why is fasting singled out for Himself, amongst other deeds, in this hadith? And how will Allah s.w.t. reward us on the Day of Judgment for our fast? Our great scholars have a number of answers, and one of them is this:
On the Day of Judgment, people will demand their rights from one another. Anyone whom we have wronged / oppressed will demand for their compensation, so our good deeds will be taken and given to those whom we have wronged (may Allah s.w.t. save us) until there is not a single good deed left to give.
EXCEPT for fasting, for it will not be taken by anyone, rather it shall only be PRESERVED AND SAVED by Allah s.w.t. for the one who fasts and He s.w.t. shall reward him for it. Allah will protect it and He will not give the oppressed person authority over it, but rather the good deed of fasting shall be for its companion with Allah the Mighty and Majestic.
 Bukhari & Muslim