The Messenger of Allah (ﷺ) used to fast three days every month.
Sunan Abi Dawud Book 14, Hadith 138
← Previous Hadith The Messenger of Allah (ﷺ) used to command us to fast the days of the white (nights): thirteenth, fourteenth and fifteenth of the month. He said: This is like keeping perpetual fast.

Sunan Abi Dawud Book 14, Hadith 137 Next Hadith → The apostle of Allah (ﷺ) used to fast three days every month: Monday, Thursday and Monday in the next week.

Sunan Abi Dawud Book 14, Hadith 139