Al-Ka’as (meaning ‘Cup’) is an ablution fountain that was built by the Ayoubi Sultan Al-Adel Abu Bakr bin Ayoub in 1193 CE (589 AH). It is a circular basin surrounded by an ornamented iron fence encircled by stone stools. It contains a central fountain and a number of side faucets used for ablutions. Al-Ka’as was renovated once by Sultan Qaitbay and last by Prince Tarkz An-Nasiri in 1327 CE (728 AH).
Reference: A guide to al-Aqsa mosque – PASSIA