Sa'id bin Iyas al-Jariri سعيد بن إياس الجريري · Fasting (Kitab Al-Siyam)

The Prophet (ﷺ) said: Do not fast one day or two days just before Ramadan except in the case of a man who has been in the habit or observing a fast (on that day); and do not fast until you sight it (the moon). Then fast until you sight it. If a cloud appears on that day (i.e. 29th of Ramadan) then complete the number thirty (days) and then end the fasting: a month consists of twenty-nine days.

The Messenger of Allah (ﷺ) met me and said: Have I not been informed that you told: I shall stand at prayer all the night, and I shall fast during the day ? He said: I think so. Yes, Messenger of Allah, I have said this. He said: Get up and pray at night and sleep ; fast and break your fast ; fast three days every month: that is equivalent to keeping perpetual fast. I said: Messenger of Allah,…