Sahih Muslim
Book 13: The Book of Fasting
كتاب الصيام
285 hadith in this book
Chapter 33 The one who eats, drinks, or has intercourse by mistake does not break his fast
باب أَكْلُ النَّاسِي وَشُرْبُهُ وَجِمَاعُهُ لاَ يُفْطِرُ
Abu Huraira reported Allah's Messenger (ﷺ) as saying: If anyone forgets that he is fasting and eats or drinks he should complete his fast, for it is only Allah Who has fed him and given him drink.
وَحَدَّثَنِي عَمْرُو بْنُ مُحَمَّدٍ النَّاقِدُ، حَدَّثَنَا إِسْمَاعِيلُ بْنُ إِبْرَاهِيمَ، عَنْ هِشَامٍ الْقُرْدُوسِيِّ، عَنْ مُحَمَّدِ بْنِ سِيرِينَ، عَنْ أَبِي هُرَيْرَةَ، - رضى الله عنه - قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَنْ نَسِيَ وَهُوَ صَائِمٌ فَأَكَلَ أَوْ شَرِبَ فَلْيُتِمَّ صَوْمَهُ فَإِنَّمَا أَطْعَمَهُ اللَّهُ وَسَقَاهُ " .
Hadith text, translations and grading are courtesy of Sunnah.com.