The Prophet ﷺ used to perform ablution with a mudd of water and bathe with a saa.
حدثنا أحمد بن منيع وعلي بن حجر قالا حدثنا إسمعيل ابن علية عن أبي ريحانة
أن النبي ﷺ كان يتوضأ بالمد ويغتسل بالصاع
Muslim also narrated it in the Book of Menstruation, chapter on the recommended amount of water for the ghusl of janaba, hadith 326, from Ali bin Hajar with the same wording.On this subject there are also narrations from Ayesha [Bukhari, hadith 251, and Muslim, 320, 321], Jabir [Abu Dawud, hadith 93, and Baghawi in Sharh al-Sunnah, 2/54, hadith 280], and Anas bin Malik [Bukhari, hadith 201, and Muslim, hadith 325].