´It was narrated that Abu Dharr said:` "The Messenger of Allah commanded us to fast the three days of Al-Bid, the thirteenth, fourteenth and fifteenth."
Hadith Referenceسنن نسائي / كتاب الصيام / 2424
Hadith Gradingالألبانی:حسن | زبیر علی زئی:إسناده حسن
´It was narrated that Musa bin Talhah said:` "I heard Abu Dharr, at Ar-Rabadhah, saying: 'The Messenger of Allah said: if you want to fast at any time during the monthm then fast on the thirteenth, fourteenth and fifteenth."'