Sunan an-Nasa'i 388
سنن النسائي#388SahihIt was narrated from 'Aishah:"The Messenger of Allah (ﷺ) used to put his head out of the Masjid while he was performing I'tikaf, and I would wash it, while I was menstruating
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: 3:41