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.
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 " .
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Zakat (Kitab Al-Zakat) • Hadith 1687