Hadith: The Prophet (may Allah's peace and blessings be upon him) used to take a ritual bath with one Sā‘ of water up to five Mudd and used to perform ablution with one Mudd

عن أنس رضي الله عنه قال: «كان النبي صلى الله عليه وسلم يغسل، أو كان يغْتَسِل، بالصَّاع إلى خَمْسة أمداد، ويَتَوضأ بالمُدِّ».
[صحيح] - [متفق عليه]

Anas (may Allah be pleased with him) reported: The Prophet (may Allah's peace and blessings be upon him) used to take a ritual bath with one Sā‘ of water up to five Mudd and used to perform ablution with one Mudd.
Sahih/Authentic. - [Al-Bukhari and Muslim]

Explanation

Anas (may Allah be pleased with him) narrated that the Prophet (may Allah's peace and blessings be upon him) used to bathe with one Sā‘ up to five Mudd of water. This indicates that he used to economize on water used in purification. He would bathe using one Sā‘ of water, which is four Mudd, or sometimes he would use five Mudd if needed. In ablution, he would use only one Mudd, which is three quarters of a liter.