It was
narrated from ‘Abdul-Malik bin Minhal, from his father that:
The
Messenger of Allah (ﷺ) used to enjoin fasting the bright days –
the thirteenth, fourteenth and fifteenth (when the moon is full). He
said: “It is like fasting for a lifetime.” Another chain from 'Abdul-Malik bin Qatadah bin Malhan Al-Qaisi, from his father, from the Prophet (ﷺ) with similar wording. Ibn Majah said: Shu'bah erred (in the name of one of the narrators)and Hammam was correct.