It is said to the author of the book: The Bakriyyah and the Ibāḍiyyah have claimed that the Prophet ﷺ explicitly appointed Abū Bakr, and you have denied this—just as we deny that Abū ʿAbd Allāh designated either of the two you mentioned. So clarify your proof for us and explain the distinction between you and the Bakriyyah and the Ibāḍiyyah, so that we may show you in kind the distinction between us and those whom you named.

It is also said to the author of the book: You are a man who claims that Jaʿfar b. Muḥammad followed the Zaydī school and did not claim the Imamate in the way the Imamiyyah describe. However, those who claim the Imamate of Muḥammad b. Ismāʿīl b. Jaʿfar b. Muḥammad say the opposite of what you and your companions say, and they assert that their forefathers transmitted it from him. So explain the distinction between you and them, and we will present a better one in return. Be fair to yourself—that is more fitting for you. Another difference is that the companions of Muḥammad b. Jaʿfar and ʿAbd Allāh b. Jaʿfar acknowledge that al-Ḥusayn designated ʿAlī, and that ʿAlī designated Muḥammad, and Muḥammad designated Jaʿfar. Our evidence that Jaʿfar designated Mūsā is exactly the same as their evidence that al-Ḥusayn designated ʿAlī. Moreover, when the Imam is publicly present and his Shīʿa refer to him, his knowledge becomes evident, and his understanding of religion is made manifest. We found that the narrators of traditions and transmitters of reports conveyed from Mūsā knowledge of ḥalāl and ḥarām that is widely recorded and well known, and his personal merit was clear to both elite and common folk. These are the signs of the Imamate, and when we found them in Mūsā and not in others, we knew he was the Imam after his father and not his brother.

Another point: ʿAbd Allāh b. Jaʿfar died without leaving a male heir and without designating anyone. Those who had claimed his Imamate then returned to the Imamate of Mūsā . The distinction between our reports and theirs is that reports do not yield certainty unless they are transmitted by individuals whose reliability removes all doubt. We do not dispute their predecessors; rather, we ask that in our time they present transmitters of traditions and reports from among their adherents in numbers sufficient to establish tawātur (mass transmission), just as we are able to do. If they can do so, let them present it. If they cannot, then the difference between us and them in our respective generations is clear. What lies beyond that is up to them. This is clear, and praise be to Allah.

As for those who stopped at Mūsā , their case is like those who stopped at Abū ʿAbd Allāh . We did not witness the deaths of any of the Imams directly; their deaths were known to us through reliable reports. So if someone stops at any one of them, we ask him for the distinction between his position and that of those who stopped at others—something they are unable to answer. Then the author of the book said: Among them is a group who affirmed Mūsā and followed his son ʿAlī b. Mūsā after him, excluding the rest of Mūsā’s children, claiming that he deserved it through inheritance and designation, and that it passed through his descendants until it reached al-Ḥasan b. ʿAlī , for whom they claimed a son and named him al-Khalaf al-Ṣāliḥ, who died before his father. Then they reverted to his brother al-Ḥasan, invalidating what they had imagined about Muḥammad. They said: Allah changed His will from Muḥammad to al-Ḥasan, just as He changed it from Ismāʿīl b. Jaʿfar to Mūsā, since Ismāʿīl died in Jaʿfar’s lifetime. When al-Ḥasan b. ʿAlī died in the year 263 AH, some of his companions returned to the Imamate of Jaʿfar b. ʿAlī, just as the companions of Muḥammad b. ʿAlī had returned to al-Ḥasan after Muḥammad’s death. Others claimed that Jaʿfar b. ʿAlī deserved the Imamate by inheritance and designation from his father ʿAlī b. Muḥammad, rather than from his brother al-Ḥasan, and they transmitted it in the lineage of Jaʿfar by inheritance and designation. All of these sects dispute one another over Imamate, declaring each other disbelievers, rejecting one another’s leaders, and each group claiming the Imamate for its figure based on inheritance, designation, and alleged knowledge of the unseen—claims that are outdone by fables. No group has proof for what it claims, nor any evidence apart from inheritance and designation. Their only proof is testimony on their own behalf without any independent support—mere claims without truth, assertions without evidence. If any group has a real proof beyond inheritance and designation, it must be established. If not, then the validity of Imamate falls apart due to the sheer number of claimants. There is no basis to accept the claim of one group over another when their claims are identical—especially when they all agree on declaring one another false, while each one is isolated in what it claims.