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عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ: «مَنْ نَسِيَ وَهُوَ صَائِمٌ، فَأَكَلَ أَوْ شَرِبَ، فَلْيُتِمَّ صَوْمَهُ، فَإِنَّمَا أَطْعَمَهُ اللهُ وَسَقَاهُ».

The Prophet (may Allah's peace and blessings be upon him) clarified that whoever eats or drinks forgetfully while fasting, whether the fast is obligatory or voluntary, should complete his fast and not break it because he did not intend to break the fast; rather, it is sustenance that Allah provided him with, and it is Allah Who fed him and gave him drink.

• The validity of the fast of whoever eats or drinks forgetfully.
• Whoever eats or drinks forgetfully incurs no sin because he does not do this by his choice.
• The kindness of Allah towards His slaves and how He facilitates things for them and removes hardship and difficulty from them.
• The fasting person does not break his fast by any of the fast invalidators unless three conditions are met: 1. Being aware; if he is ignorant, the fast is not broken. 2. Remembering; if he is forgetful, his fast is valid and he does not need to make up for it. 3. Willingness; not under compulsion, meaning he consumes the invalidating means by choice.

صحيح البخاري (3/ 31) (1933). صحيح مسلم (2/ 809) (1155). تيسير العلام، لعبد الله البسام (ص319). تنبيه الأفهام شرح عمدة الأحكام، لابن عثيمين (3/ 422). خلاصة الكلام على عمدة الأحكام، لفيصل آل مبارك (ص148).