Sahih al-Bukhari 1933

Arabic

حَدَّثَنَا عَبْدَانُ، أَخْبَرَنَا يَزِيدُ بْنُ زُرَيْعٍ، حَدَّثَنَا هِشَامٌ، حَدَّثَنَا ابْنُ سِيرِينَ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ إِذَا نَسِيَ فَأَكَلَ وَشَرِبَ فَلْيُتِمَّ صَوْمَهُ، فَإِنَّمَا أَطْعَمَهُ اللَّهُ وَسَقَاهُ ‏"‏‏.‏

English translation

Narrated Abu Huraira:The Prophet (ﷺ) said, "If somebody eats or drinks forgetfully then he should complete his fast, for what he has eaten or drunk, has been given to him by Allah

Reference: Sahih al-Bukhari 1933, Book of Fasting. English translation by Dr. Muhammad Muhsin Khan.