Musnad Ahmad 30:2014

Hawdha narrated to us, he said: ‘Awf narrated to us, from Khallas and Muhammad, from Abu Hurayrah, from the Prophet, may God bless him and grant him peace, and from al-Hasan, from the Prophet, may God bless him and grant him peace, who said: "If one of you fasts a day and forgets, then eats and drinks, let him complete his fast, for it is only God who fed him and gave him drink."