the Messenger of Allah saw some people gathered around a man, so he asked (what was happening) and they said: "It is a man who is exhausted because of fasting." The Messenger of Allah said: "It is not righteousness to fast when traveling."
أَنَّ رَسُولَ اللَّهِ ﷺ رَأَى نَاسًا مُجْتَمِعِينَ عَلَى رَجُلٍ فَسَأَلَ فَقَالُوا رَجُلٌ أَجْهَدَهُ الصَّوْمُ قَالَ رَسُولُ اللَّهِ ﷺ لَيْسَ مِنَ الْبِرِّ الصِّيَامُ فِي السَّفَرِ