The Messenger of Allah (ﷺ) took a bath with one Sa` of water because of sexual intercourse and performed ablution with one Mudd.
Sahih Muslim Book 3, Hadith 60
← Previous Hadith The Apostle of Allah (ﷺ) performed ablution with one Mudd and took bath with a Sa' up to five Mudds.

Sahih Muslim Book 3, Hadith 59 Next Hadith → The Messenger of Allah (ﷺ) took a bath with one Sa' of water and performed ablution with one Mudd (of water) ; and in the hadith narrated by Ibn Hujr the words are: One Mudd sufficed for his (Holy Prophet's) ablution. And Ibn Hujr said that (his Shaikh) Isma'il was much advanced in age, and it was because of this that he could not fully rely on him for this tradition.

Sahih Muslim Book 3, Hadith 61