"One of the wives of the Prophet took a bath from a large vessel, then the Prophet came and had a bath or ablution, and she said: 'O Messenger of Allah, I was sexually impure.' He said: 'Water does not become impure.'"  

اغْتَسَلَ بَعْضُ أَزْوَاجِ النَّبِيِّ ﷺ فِي جَفْنَةٍ فَجَاءَ النَّبِيُّ ﷺ لِيَغْتَسِلَ أَوْ يَتَوَضَّأَ فَقَالَتْ يَا رَسُولَ اللَّهِ إِنِّي كُنْتُ جُنُبًا فَقَالَ الْمَاءُ لاَ يُجْنِبُ  

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."  

أَنَّ امْرَأَةً مِنْ أَزْوَاجِ النَّبِيِّ ﷺ اغْتَسَلَتْ مِنْ جَنَابَةٍ فَتَوَضَّأَ أَوِ اغْتَسَلَ النَّبِيُّ ﷺ مِنْ فَضْلِ وَضُوئِهَا  

the Prophet performed ablution with the water left over after she had taken a bath to cleanse herself from sexual impurity.  

عَنْ مَيْمُونَةَ زَوْجِ النَّبِيِّ ﷺ أَنَّ النَّبِيَّ ﷺ تَوَضَّأَ بِفَضْلِ غُسْلِهَا مِنَ الْجَنَابَةِ