All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
This story is reported by Muslim but without the mention of the story of Umm Salamah so it is wrong to attribute the whole story to Imaam Muslim. Nevertheless, the story of Umm Salamah was reported by Imaam Ahmad in his Musnad, and its chain of narrators is Dha’eef [weak] but Al-Arna’oot classified it as Saheeh due to its various routes of narration.
However, there is nothing in this story that proves that the wives of the Prophet are not among the members of his household [Ahlul-Bayt]. Rather, there is evidence that they are among Ahlul-Bayt, as we already clarified in Fatwa 87409, so please refer to it.
The Hadeeth that is mentioned is not clear evidence that his wives are not among Ahlul-Bayt. Rather, there is another authentic wording of this Hadeeth which proves that the wives of the Prophet are among Ahlul-Bayt. We mean the narration reported by Al-Bayhaqi in which it is mentioned that Umm Salamah said, “I said, 'O Prophet of Allaah, am I not one of Ahlul-Bayt?' Thereupon, the Prophet replied: ''Yes, In shaa' Allaah (Allaah willing).”
Then Al-Bayhaqi said, “Abu ‘Abdullaah (meaning himself) said, 'The chain of narration of this Hadeeth is Saheeh, and its narrators are trustworthy. Besides, some Ahaadeeth were narrated supporting it and others contradicting it, but they are not proved to be authentic and the Book of Allaah contains what clarifies what we indicated here that the Prophet used the word ‘Ahlul-Bayt’ to mean his wives or that his wives are included in it.'”
Allaah Knows best.