Quran and Sunnah

O ye who believe! fasting is prescribed to you as it was prescribed to those before you that ye may (learn) self-restraint. 

As it was prescribed: this does not mean that the Muslim fast is like the other fasts previously observed, in the number of days, in the time or manner of the fast, or in other incidents; it only means that the principle of self-denial by fasting is not a new one.