Imamate is not Rightfully Invested except In the Descendants of al-Ḥusayn to the Exclusion of the Descendants of al-Ḥasan عليهما السلام

Saʿd, from Aḥmad b. Muḥammad b. ʿĪsā, from al-Ḥusayn b. Saʿīd, from al-Qāsim b. Muḥammad, from ʿAbd al-Ṣamad b. Bashīr, from Fuḍayl Sakkara, who narrated: “I entered upon Abī ʿAbd Allāh عليه السلام, whereupon he said: “O’ Fuḍayl, do you know which thing I was looking at just before?,” so I replied: “No.” He said: “I was looking at the Book of Fāṭima عليها السلام. There is not a king who would reign but that his name, and the name of his father, is written in it, and I did not find anything in it about the offspring of al-Ḥasan عليه السلام.”