What is the authenticity of the hadith of Ibn 'Umar that men and women used to perform ablution together from a single vessel during the time of the Messenger of Allah, peace and blessings be upon him?

The aforementioned Hadith is authentic, narrated by Al-Bukhari and others, and its wording is: "Men and women used to perform ablution together during the time of the Messenger of Allah, peace and blessings be upon him." Ibn Hajar Al-Asqalani clarified that this was before the revelation of the Hijab [verse pertaining to veiling], but after its revelation, shared ablution is restricted to wives and mahrams [unmarriageable kin].