It was
narrated from Abu Hurairah that the Messenger of Allah (ﷺ)
said:
"Whoever eats out of forgetfulness while fasting, let him
complete his fast, for it is Allah Who has fed him and given him to
drink." (ID)
English reference (ID): Vol. 1, Book 7, Hadith 1673 (ID)
Arabic reference (ID): Book 7, Hadith 1743 (ID)