Sunan an-Nasa'i, Volume 1, Book 2, Hadith 347 (DarusSalam) ⓘ
It was narrated from 'Aishah that the Messenger of Allah used to perform Ghusl with a Mudd and Ghusl with approximately a Sa'.
أَخْبَرَنَا هَارُونُ بْنُ إِسْحَاقَ الْكُوفِيُّ، قَالَ حَدَّثَنَا عَبْدَةُ، - يَعْنِي ابْنَ سُلَيْمَانَ - عَنْ سَعِيدٍ، عَنْ قَتَادَةَ، عَنْ صَفِيَّةَ بِنْتِ شَيْبَةَ، عَنْ عَائِشَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يَتَوَضَّأُ بِمُدٍّ وَيَغْتَسِلُ بِنَحْوِ الصَّاعِ .
also referenced under: Hadith 346 (Reference) & Book 2, Hadith 22 (In-Book)