Alsiraj Official Website
Sayings (Hadiths) of Prophet Muhammad
About fasting
About the superiority of voluntary fast
Narrated Abu-Huraira: the Messenger of Allah said: the best fasting besides fasting in the month of Ramadan is fasting in the month of Allah, the month of Moharram, and the best prayer besides obligatory prayer is voluntary prayer by night.
(At.Termozi)
About the general ruling of Fasting
Narrated Abu-Huraira: the Prophet said: if somebody eats or drinks forgetfully then he should complete his fasting for what he has eaten or drunk has been given to him by Allah.
(Bukhari)