the Prophet commanded them to fast the three days of Al-Bid. He said: "That is (equivalent to) fasting for the whole month."
Sunan an-Nasa'i Book 22, Hadith 342
← Previous Hadith the Messenger of Allah used to enjoin (fasting) these days of Al-Bid and he said: "That is (equivalent to) fasting for the whole month."

Sunan an-Nasa'i Book 22, Hadith 341 Next Hadith → "The Messenger of Allah used to command us to fast the three days with the shining bright nights (Al-Ayam Al-Bid), the thirteenth, fourteenth and fifteenth."

Sunan an-Nasa'i Book 22, Hadith 343