Riyad as-SalihinChapter 8Hadith 563
Full Sharh — Riyad as-Salihin 563
وعن أبي هريرة رضي الله عنه عن النبي صلى الله عليه وسلم قال: "إذا نسي أحدكم فأكل أو شرب فليتم صومه فإنما أطعمه الله وسقاه" ((متفق عليه))
English Translation
Abu Hurairah (May Allah be pleased with him) reported:: The Prophet (ﷺ) said, "If any one of you forgetfully eats or drinks (while observing fasting) he should complete his Saum (fasting), for Allah has fed him and given him to drink.".
Source
Riyad as-Salihin(رياض الصالحين)
The Book of Virtues
Hadith Number
563