Sunan an-Nasa'i 264
سنن النسائي#264SahihIt was narrated from Anas that the Messenger of Allah (ﷺ) used to (go around) all his wives and perform Ghusl once
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: 1:265