(Quran 2.285) The month of Ramadan, in which the Quran was brought down, a guidance for the people, and clarification of the guidance and the criterion. Therefore, those of you who witness the month shall fast it. And those who are ill or travelling, then an equal number of other days. God wants ease for you, and He does not want hardship for you, and so that you may complete the count, and to exalt God for guiding you, and that you may be thankful.
The fourth “pillar” or foundation of Islam is the fasting of the month of Ramadan. As with all other aspects of the religion, all the details related to Fasting are found in the Quran.