To perform ablution with one Mudd of water. (Mudd is practically 2/3 of the kilogram)

Sahih al-Bukhari · Book 4 · Hadith 201

حَدَّثَنَا أَبُو نُعَيْمٍ، قَالَ حَدَّثَنَا مِسْعَرٌ، قَالَ حَدَّثَنِي ابْنُ جَبْرٍ، قَالَ سَمِعْتُ أَنَسًا، يَقُولُ كَانَ النَّبِيُّ صلى الله عليه وسلم يَغْسِلُ ـ أَوْ كَانَ يَغْتَسِلُ ـ بِالصَّاعِ إِلَى خَمْسَةِ أَمْدَادٍ، وَيَتَوَضَّأُ بِالْمُدِّ‏.‏

Narrated Anas: The Prophet (ﷺ) used to take a bath with one Sa` up to five Mudds (1 Sa` = [??] Mudds) of water and used to perform ablution with one Mudd of water.