Ahmed bin Harb bin Muhammad أحمد بن حرب بن محمد · The Book of Fasting

"Whoever fasts one day in the cause of Allah, the Mighty and Sublime, Allah will separate his face from the fire by (a distance of) seventy years."

"The Messenger of Allah said on the day of Ashura: Is there anyone among you who has eaten today?' They said: Some of us are fasting and some of us are not.' He said: 'Do not eat for the rest of the day, and send word to the people of Al-Al-Arud telling them not to eat for the rest of the day."'

"Whoever does not intend to fast from the night before, should not fast." (Daif)