(28) CHAPTER. To observe Saum [(fasts) (according to Islamic teachings)] during the month of Ramadan (sincerely and faithfully) hoping for Allah's Rewards only, is a part of faith.
Narrated Abu Huraira: Allah's Apostle said, Whoever observes fasts during the month of Ramadan out of sincere faith, and hoping to attain Allah's rewards, then all his past sins will be forgiven.