Sunan an-Nasa'i, Volume 3, Book 22, Hadith 2285 (DarusSalam) ⓘ

It was narrated that Anas bin Malik said: "We were with the Messenger of Allah on a journey, and some of us were fasting and some of us were not. We made a stop on a hot day and looked for shade. Those who were fasting fell to the ground, but those who were not fasting got up and watered the animals. The Messenger of Allah said: 'Those who were not fasting today have taken the reward.""

أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا أَبُو مُعَاوِيَةَ، قَالَ حَدَّثَنَا عَاصِمٌ الأَحْوَلُ، عَنْ مُوَرِّقٍ الْعِجْلِيِّ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ كُنَّا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي السَّفَرِ فَمِنَّا الصَّائِمُ وَمِنَّا الْمُفْطِرُ فَنَزَلْنَا فِي يَوْمٍ حَارٍّ وَاتَّخَذْنَا ظِلاَلاً فَسَقَطَ الصُّوَّامُ وَقَامَ الْمُفْطِرُونَ فَسَقَوُا الرِّكَابَ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ ذَهَبَ الْمُفْطِرُونَ الْيَوْمَ بِالأَجْرِ ‏" ‏ ‏.‏