The Prophet said: "A woman may not fast a day - other than in the month of Ramadan - while her husband is present, except with his permission."  

عَنِ النَّبِيِّ ﷺ قَالَ لاَ تَصُومُ الْمَرْأَةُ وَزَوْجُهَا شَاهِدٌ يَوْمًا مِنْ غَيْرِ شَهْرِ رَمَضَانَ إِلاَّ بِإِذْنِهِ قَالَ وَفِي الْبَابِ عَنِ ابْنِ عَبَّاسٍ وَأَبِي سَعِيدٍ