The Book of Menstruation
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا وَكِيعٌ، عَنْ مِسْعَرٍ، عَنِ ابْنِ جَبْرٍ، عَنْ أَنَسِ، قَالَ كَانَ النَّبِيُّ صلى الله عليه وسلم يَتَوَضَّأُ بِالْمُدِّ وَيَغْتَسِلُ بِالصَّاعِ إِلَى خَمْسَةِ أَمْدَادٍ .Anas said:The Apostle of Allah (ﷺ) performed ablution with one Mudd and took bath with a Sa' up to five Mudds
From Sahih Muslim, whose reports the scholars accept as authentic.