The Book of Menstruation
وَحَدَّثَنَاهُ عَمْرٌو النَّاقِدُ، حَدَّثَنَا مُعَاوِيَةُ بْنُ عَمْرٍو، حَدَّثَنَا زَائِدَةُ، عَنْ هِشَامٍ، قَالَ أَخْبَرَنِي عُرْوَةُ، عَنْ عَائِشَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ إِذَا اغْتَسَلَ مِنَ الْجَنَابَةِ بَدَأَ فَغَسَلَ يَدَيْهِ قَبْلَ أَنْ يُدْخِلَ يَدَهُ فِي الإِنَاءِ ثُمَّ تَوَضَّأَ مِثْلَ وُضُوئِهِ لِلصَّلاَةِ .Urwa has narrated it on the authority of 'A'isha that when Allah's Messenger (ﷺ) took a bath because of sexual intercourse, he first washed his hands before dipping one of them into the basin, and then performed ablu- tion as is done for prayer
From Sahih Muslim, whose reports the scholars accept as authentic.