وَعَنْ جَابِرٍ قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فِي سَفَرٍ فَرَأَى زِحَامًا وَرَجُلًا قَدْ ظُلِّلَ عَلَيْهِ فَقَالَ: «مَا هَذَا؟» قَالُوا: صَائِمٌ. فَقَالَ: «لَيْسَ مِنَ الْبِرِّ الصَّوْمُ فِي السَّفَرِ»

Jabir said that in the course of a journey God’s messenger saw a crowd and a man who had been put in the shade. On asking the reason and being told that he was fasting he said, “Fasting while on a journey is not a part of righteousness.” (Bukhari and Muslim.)