The significance of fasting in Islam can be deduced from many verses of the Holy Qur’an. For example, the verses 2:45 reads:
استعينوا بالصبر و الصلوه و انھا لکبيره ا علی الخاشعين
And take recourse in patience and prayer, and it is indeed hard except for the humble. Download the whole text here: 42-Merits of fasting