The Messenger of Allah ﷺ used to perform the ritual bath for major impurity from a vessel known as the faraq.
أن رسول الله ﷺ كان يغتسل من إناء-وهو الفرق- من الجنابة.
No references are available.
Malik related it in "Purification" (68) from Ibn Shihab, from Urwa, from Ayesha. And through Malik's route, Muslim related it in "Menstruation" (319). A faraq is three sa's.