Narrated 'Abd Allah b. 'Amr b. al-'As: 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, I have more power than that. He said: Then fast one day and break your fast one day. That is the most moderate fast ; that is the fast of Dawud (David). He said: I have more power than that. The Messenger of Allah (ﷺ) said: There is no fast more excellent that it.
Sunan Abi Dawud, 2427Sahih (Al-Albani)صحيح (الألباني)
