As for Husayn, who was killed: if this means al-Husayn ibn ‘Alī, his standing is too high for him to narrate through an intermediary from Asmā’ bint ‘Umays, whether Fātimah was his sister or his daughter. Had this story been true, he would have known more about it than these people. He would have heard it from his father and others, and from Asmā’, his father’s wife, and other women. He would not have narrated it through his daughter or sister from Asmā’, his father’s wife.
But this is not al-Husayn ibn ‘Alī; rather, it is someone else, or it is ‘Abd Allāh ibn al-Hasan, Abū Ja‘far. Both have their parallels in others like them.
A hadith is established only through a narrator known to be upright, accurate and trustworthy, whom hadith scholars recognize as such. Merely knowing his lineage does not establish this, whoever he may be. Among the sons of the Companions and the Successors are men whose hadiths cannot be used as evidence, even though their fathers were among the finest Muslims.
All this assumes that ‘Alī ibn Hāshim actually narrated it. Otherwise, the narrator reporting from him is ‘Abbād ibn Ya‘qūb al-Rawājinī. Ibn Hibbān said (1): “He was a Rāfidī (* propagandist who transmitted rejected reports from well-known narrators, and therefore deserved to have his narrations abandoned.”
Ibn ‘Adī said: “He narrated hadiths that were rejected as objectionable, concerning the virtues *) (2) of the Prophet’s household and the faults of others.” Al-Bukhārī and others narrated from him hadiths whose authenticity was known. Apart from that, Qāsim al-Mutarriz’s account of his saying, “‘Alī dug out the sea, and al-Hasan made water flow into it,” plainly impugns his credibility (3).