What is the divine reward for those who observe the fasts in the month of Ramadan out of sincere faith and hoping to attain Allah's rewards, according to the teaching of Prophet Muhammad (saw)?
      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."