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

English translation · Sunan Ibn Majah