he asked Ibn Al-Musaiyab about fasting on a journey, so he narrated to him that Umar bin Al-Khattab said: "We fought in two battles along with the Messenger of Allah during Ramadan; the Day of Badr, and the Conquest (of Makkah), so we broke our fast during them."  

غَزَوْنَا مَعَ رَسُولِ اللَّهِ ﷺ فِي رَمَضَانَ غَزْوَتَيْنِ يَوْمَ بَدْرٍ وَالْفَتْحِ فَأَفْطَرْنَا فِيهِمَا قَالَ وَفِي الْبَابِ عَنْ أَبِي سَعِيدٍ