حَدَّثَنَا الْحَسَنُ بْنُ عَلِيٍّ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنْ هَمَّامِ بْنِ مُنَبِّهٍ، قَالَ سَمِعْتُ أَبَا هُرَيْرَةَ، يَقُولُ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا أَنْفَقَتِ الْمَرْأَةُ مِنْ كَسْبِ زَوْجِهَا مِنْ غَيْرِ أَمْرِهِ فَلَهَا نِصْفُ أَجْرِهِ "
Abu Hurairah reported The Messenger of Allah (ﷺ) as saying When a woman gives something her husband has earned without being commanded by him to do so, she has half his reward.
Reference: Sunan Abi Dawud 1687
In-book : Book 9, Hadith 132
English translation : Book 9, Hadith 1683