Mishkat al-Masabih 7 Fasting كتاب الصوم 71

وَعَنْ عَبْدِ الرَّحْمَنِ بْنِ عَوْفٍ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «صَائِمُ رَمَضَانَ فِي السَّفَرِ كَالْمُفْطِرِ فِي الْحَضَرِ» . رَوَاهُ ابْن مَاجَه

‘Abd ar-Rahman b. ‘Auf reported God’s messenger as saying, “One who fasts in Ramadan while travelling is like one who breaks his fast when not travelling.” Ibn Majah transmitted it.