Why did the women uncover their faces before the Messenger of Allah, peace be upon him, and cover them before Umar, may Allah be pleased with him? And what is the response to the opinion that they were his wives or that the matter was specific to the Prophet, peace be upon him? And is this hadith considered evidence that the niqab is not obligatory?

We do not agree with describing those who believe the covering of a woman's face is obligatory as being astray; due to the existence of strong evidence supporting this, and thus, one must seek Allah's forgiveness and recognize the stature of scholars. Regarding the hadith (definition) "Qaman yabtadiran al-hijab (definition)," the hijab means covering, not a garment that covers the face, and this is confirmed by multiple narrations. Describing Ibn Hajar as mistaken is purely a mistake, and his words are valid and plausible; as he interpreted "yastakthirnah" as seeking grants and maintenance, and many commentators agreed with him on this. Umar's address to the Mothers of the Believers with "O enemies of themselves" was permissible due to his special status. As for Ibn Hajar's statement that the permissibility of being alone with a non-mahram (definition) woman and looking at her was among the Prophet's (peace be upon him) unique characteristics, it is a respected opinion, and scholars have affirmed it.