(13) باب الْقَدْرِ الَّذِي يَكْتَفِي بِهِ الإِنْسَانُ مِنَ الْمَاءِ لِلْوُضُوءِ وَالْغُسْلِ
It was narrated from 'Aishah that the Messenger of Allah (ﷺ) used to perform Ghusl with a Mudd and Ghusl with approximately a Sa'.
Reference: Sunan an-Nasa'i 346
In-book reference: Book 2, Hadith 22
English translation: Vol. 1, Book 2, Hadith 347