(26) باب الصَّائِمِ إِذَا أَكَلَ أَوْ شَرِبَ نَاسِيًا
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
In-book reference: Book 30, Hadith 40
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 31, Hadith 154