Abu Hurairah (RAA) narrated that The Messenger of Allah said, "A woman is not to fast (even) for one day while her husband is present except with his permission" Agreed upon and the wording is from Al-Bukhari. Abu Dawud’s version states, “unless it is during Ramadan (then she does not need his permission as it is obligatory fasting).’’

وَعَنْ أَبِي هُرَيْرَةَ ‏- رضى الله عنه ‏- أَنَّ رَسُولَ اَللَّهِ ‏- صلى الله عليه وسلم ‏-قَالَ: { لَا يَحِلُّ لِلْمَرْأَةِ أَنْ تَصُومَ وَزَوْجُهَا شَاهِدٌ إِلَّا بِإِذْنِهِ } مُتَّفَقٌ عَلَيْهِ, وَاللَّفْظُ لِلْبُخَارِيِّ [1]‏ .‏ وَزَادَ أَبُو دَاوُدَ: { غَيْرَ رَمَضَانَ } [2]‏ .‏