Asim al-Ahwal عاصم الأحول · The Book on Fasting

the Prophet said: "When one of you breaks his fast, then let him do so with dried dates. And whoever does not find dates, then water, for it is purifying."

"The Messenger of Allah would fasting during the beginning of every month for three days, and Friday was the least of the days that he did not fast."

"The Messenger of Allah said: 'Whoever fasts three days in every month, then that is (similar to) fasting every day.' Then Allah Mighty and Sublime is He, attested to that in His Book, by revealing: Whoever brings a good deed, shall have ten times the like thereof. So a day is like ten."

"I said to Ubayy bin Ka'b: 'O Abu Al-Mundhir! How do you know that it is the night of the twenty-seventh?' He said: 'Rather, the Messenger of Allah informed us that it is a night (after which) the sun rises without rays, so we counted and we remembered it. By Allah! Ibn Mas'ud learned that it is in Ramadan and that it is the nigh of the twenty-seventh, but he did not want to inform you lest you would depend…