It is dictated in the sacred Hadis Shareef-
“Every good deed of son of Adam is increased from ten to seven hundred times. Allah Pak says, except for fasting. Because fasting is kept for me only, and I will give it by myself as much as I can. He (the servent) refrains from food and drinks for me only. “(Bukhari Shareef and Muslim Shareef)
To know the sacred Ahkam, Massail and Fazail of sacred month Rwamadan, visit: http://ahkamurrwamadan.com