حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا أَبُو أُسَامَةَ، عَنْ عَوْفٍ، عَنْ خِلاَسٍ، وَمُحَمَّدِ بْنِ سِيرِينَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ‏"‏ مَنْ أَكَلَ نَاسِيًا وَهُوَ صَائِمٌ فَلْيُتِمَّ صَوْمَهُ فَإِنَّمَا أَطْعَمَهُ اللَّهُ وَسَقَاهُ ‏"‏ ‏.‏

It was narrated from Abu Hurairah that the Messenger of Allah (PBUH) 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." Translation Not Available

Book Ref: Sunan Ibn Majah Book 7 Hadith 1673
Web Ref:  Sunan Ibn Majah Vol 1 Book 7 Hadith 1673