Sahih
حَدَّثَنَا عَلِيُّ بْنُ مُحَمَّدٍ، حَدَّثَنَا وَكِيعٌ، عَنْ سُفْيَانَ، عَنْ سِمَاكِ بْنِ حَرْبٍ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ امْرَأَةً، مِنْ أَزْوَاجِ النَّبِيِّ ـ صلى الله عليه وسلم ـ اغْتَسَلَتْ مِنْ جَنَابَةٍ فَتَوَضَّأَ أَوِ اغْتَسَلَ النَّبِيُّ ـ صلى الله عليه وسلم ـ مِنْ فَضْلِ وَضُوئِهَا .
It was narrated from Ibn 'Abbas that:One of the wives of the Prophet took a bath to cleanse herself from sexual impurity, then the Prophet performed ablution and had a bath with the water left over from her ablution