It is permissible to fast or not to fast during Ramadan for one who is travelling for no sinful purpose, if his journey is two stages or further. But it is better for the one who is able to fast without suffering any harm to do so, and the one for whom it is difficult may break the fast

حَدَّثَنَا نَصْرُ بْنُ عَلِيٍّ الْجَهْضَمِيُّ، حَدَّثَنَا بِشْرٌ، - يَعْنِي ابْنَ مُفَضَّلٍ - عَنْ أَبِي مَسْلَمَةَ، عَنْ أَبِي نَضْرَةَ، عَنْ أَبِي سَعِيدٍ، - رضى الله عنه - قَالَ كُنَّا نُسَافِرُ مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي رَمَضَانَ فَمَا يُعَابُ عَلَى الصَّائِمِ صَوْمُهُ وَلاَ عَلَى الْمُفْطِرِ إِفْطَارُهُ ‏.‏