Sunan an-Nasa'i 345
سنن النسائي#345SahihIt was narrated that 'Abdullah bin Jabr said:"I heard Anas bin Malik say: 'The Messenger of Allah (ﷺ) used to perform Wudu' with a Makkuk (cup) and Ghusl with five Makkuks (cups)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih
In-book reference: 2:21