Sahih Muslim, hadith 2618

حَدَّثَنِي عَمْرٌو النَّاقِدُ، حَدَّثَنَا إِسْمَاعِيلُ بْنُ إِبْرَاهِيمَ، عَنِ الْجُرَيْرِيِّ، عَنْ أَبِي نَضْرَةَ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، - رضى الله عنه - قَالَ كُنَّا نَغْزُو مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي رَمَضَانَ فَمِنَّا الصَّائِمُ وَمِنَّا الْمُفْطِرُ فَلاَ يَجِدُ الصَّائِمُ عَلَى الْمُفْطِرِ وَلاَ الْمُفْطِرُ عَلَى الصَّائِمِ يَرَوْنَ أَنَّ مَنْ وَجَدَ قُوَّةً فَصَامَ فَإِنَّ ذَلِكَ حَسَنٌ وَيَرَوْنَ أَنَّ مَنْ وَجَدَ ضَعْفًا فَأَفْطَرَ فَإِنَّ ذَلِكَ حَسَنٌ ‏.‏

Abu Sa'id al-Khudri (Allah be pleased with him) reported:We went out on an expedition with the Messenger of Allah (ﷺ) during Ramadan. Some of us observed the fast and some of us broke it. Neither the observer of the fast had any grudge against one who broke it, nor the breaker of the fast had any grudge against one who had fasted They knew that he who had strength enough (to bear its rigour) fasted and that was good, and they also found that he who felt weakness (and could not bear the burden) broke it, and that was also good