Designation According to the majority of the available sources, al-Sadiq had indeed designated al-Mubarak by
nass (divine decree) as his successor in
Imamate. This fact was accepted as the formal act of nass required by Shia theory and was therefore a designation by an infallible Imam of the new Imam who would inherit the full powers of the Imamate. Al-Mubarak was thus not only al-Sadiq's choice but was God's choice as well. This designation, in fact, forms the basis of Isma'ili claims and which should have settled the question of al-Sadiq's succession in due course. According to the Isma'ili tradition, when al-Mubarak was seven years of age, al-Sadiq declared his Imamate. He was separated from his other brothers and kept away from contact with the public. Al-Sadiq himself undertook his education. As
da'i Idris observes, this declaration was made secretly on the basis of
taqiyya. Only certain selected followers of al-Sadiq knew this fact. Apparently, though, al-Sadiq did not appoint another in place of al-Mubarak and the theoretical argument by which he might have done so is, generally speaking, missing; although the later
Twelver Shias claimed such a nass for
Musa ibn Ja'far al-Kazim, the younger half brother of al-Mubarak, producing several
hadiths to this effect. Twelver writers like
al-Nawbakhti (d. 922) admitted as much even a hundred years after the fact. After the death of al-Sadiq a great confusion arose amongst his sons as each of his surviving sons claimed the Imamate but could not produce sufficient credentials, and so their followers melted away in a short period except for two candidates: al-Mubarak and al-Kazim. Al-Mubarak was some twenty-five years older than his half-brother al-Kazim, who was born in 128/745–46 to a
Berber slave-girl. Various historians relate that "all" of the sons of al-Sadiq contended for the position. In
Kalām-i Pīr, an Isma'ili work wrongly attributed to
Nasir Khusraw (), there is an account of this contest, which was again carried for decision to the
Black Stone at
Mecca, as had been done by
Zayn al-Abidin and
Muhammad ibn al-Hanafiyya. This time the decision was in favour of al-Mubarak, after which al-Kazim swears
allegiance to him. Various reasons are given as an explanation for altering the nass al-Sadiq had given to al-Mubarak. That most frequently used by historians, mostly Sunni and Twelver, is that al-Mubarak had been drinking, to which the Isma'ili could reply, that the Imam being infallible would know a truth concerning drinking beyond the
zahir command to abstain from it. More likely, It deserves to note that some bombastic stories of al-Mubarak's indulgence in drink and his alleged association with the extremists have been condemned by many historians. Mufaddal ibn Umar al-Sayrafi however relates that al-Sadiq, in view of his son's piety had already warned the people in Medina that, "Do not wrong Isma'il" (la tajafu Isma'ila). With regard to the Twelver Shia claims that al-Mubarak had pre-deceased al-Sadiq, the Isma'ilis believe that al-Sadiq observed "taqiya" (dissimulation) and gave a chance to his real successor to go underground so that their enemy, the Abbasids, did not pursue al-Mubarak, and that his Imamate and his activities went un-noticed. Thus al-Kazim who was believed to be poisoned by the Abbasid Caliph
Harun was in fact a veil (hījab) for al-Mubarak. The
Sunni historian
Rashid al-Din Hamadani () wrote that some Isma'ilis believed that al-Kazim willingly gave his life for the sake of his elder brother al-Mubarak, the true Imam. The Isma'ilis further argued that the Imam being ''
ma'sum (infallible) could not make an error of Judgement and therefore the first nass'' (designation) of al-Sadiq was the correct one. Thus, this group accepted al-Mubarak as their Imam and are known as Isma'iliyya or Isma'ilis.
Relations with radical Shias Al-Mubarak evidently had contacts with the activist Shias in his father's following, including
al-Mufaddal ibn Umar al-Ju'fi. According to the historian
al-Maqrizi (d. 1442), al-Mufaddal regarded al-Sadiq as God, so the Imam repudiated him and publicly cursed him. Al-Mubarak, who was reportedly involved in certain anti-Abbasid plots, may also have collaborated with
Abu al-Khattab al-Asadi, another activist Shia originally in the entourage of al-Sadiq. Abu al-Khattab had been active in the Shia group with al-Sadiq, but the latter had to repudiate him openly, because of his extremist theological view, which he had endeavoured to enforce by militant means, though Abu al-Khattab supposedly maintained that the repudiation was part of al-Sadiq's technique at preserving his true nature. The Asrār also states that al-Sadiq had to forbid al-Mubarak to go to the school which Abu al-Khattab had been conducting.
Louis Massignon (d. 1962) has suggested that Abu al-Khattab was the spiritual or adoptive father of al-Mubarak, hence his
kunya of Abu Isma'il. In this connection, he formulated a general hypothesis, contending that since the beginning of the second Islamic century, the expression anta minna Ahl al-Bayt ('you are from the Prophet's family') purportedly used by
Muhammad in reference to
Salman the Persian, and as reported in a hadith, had acquired a ritual value indicating 'spiritual adoption' amongst the revolutionary Shias, for whom real family ties were established through spiritual parentage, adoption or initiation. Possible collaboration between al-Mubarak and Abu al-Khattab remains shrouded in obscurity, despite the fact that the Twelver sources, generally hostile to the Isma'ilis, identify the nascent Isma'ili with the early
Khattabiyya; the later Isma'ilis regarded Abu al-Khattab as a heretic and repudiated the Khattabiyya.
The doctrine of bada The Twelver Shia believe that al-Sadiq revoked his first
nass in favour of al-Mubarak with radical Shias and made a second
nass in favour of his son al-Kazim. This newly contrived theory took its early nourishment among the people who lacked the concept of the Imamate. The Twelver scholar
Abdulaziz Abdulhussein Sachedina confirms the problems inherent in the doctrine of bada: "It implied God's change of mind (
bada) because of a new consideration, caused by the death of Isma'il. However, such connotations in the doctrine of bada (change of mind) raised serious questions about the nature of God's knowledge, and indirectly, about the ability of the Imams to prophesy future occurrences." Al-Sadiq is also reported to have said: "Inlillah fi kullo shain bida illah Imamah" means, "Verily, God makes changes in everything except in the matter of Imam." This point merits further indication al-Sadiq had no power to cancel, revoke or alter the first nass in favour of al-Mubarak, and therefore, the tradition of change of nass carries no historicity. Al-Nawbakhti writes in ''Kitāb Firaq al-Shī'a'' that, "Yet another version is that by appointing his son, Isma'il, as an Imam, al-Sadiq thus resigned. Isma'il was therefore a real Imam, and after him, the Imamate has to pass to his son, Muhammad." Al-Shahrastani writes in
Kitāb al-Milal wa al-Niḥal that, "Designation (nass), however, cannot be withdrawn, and has the advantage that the Imamate remains in the descendants of the person designated, to the exclusion of others. Therefore, the Imam after Isma'il is Muhammad ibn Isma'il."
Succession The Mubarakiyya claimed that, when al-Mubarak was alive, he appointed his son
Muhammad as his heir and sent his da'is to different regions to administer the oath in his name. Another proto-Isma'ili group which is recorded by the sources deemed that al-Sadiq, not al-Mubarak, designated Muhammad ibn Isma'il as the seventh Imam, and he was the last Imam and the
Mahdi who remained alive and would return as the
Qa'im. This group is said to have formed the nucleus of the
Qaramita sect which regarded Muhammad as their seventh and last Imam. Ja'far ibn Mansur al-Yaman writes in
Asrār al-Nuṭaqā' that, "Both we and you admit the tradition that when Isma'il was about to die, he summoned his son and his followers, and handed over the Imamate to him, in their presence, under the supervision of his father [al-Sadiq]. He entrusted the testimony concerning the position of his son to one of his ḥujjats [i.e. da'is], as did his forefather
Ishmael (
Isma'il) with regard to the person surnamed al-Kabsh [], appointed before him. He made him the "veil" for his heir, to distract towards him the attention of the tyrants of the time. And al-Sadiq presided over the assembly, as
Jacob (
Ya'qub) presided over the assembly of
Joseph (
Yusuf) when the latter was on his deathbed." The Mubarakiyya held that the right of the Imamate must pass from al-Mubarak, the father, to Muhammad, the son, because the Imamate could not be transferred from brother to brother after the case of Imams
al-Hasan and
al-Husayn, the sons of 'Ali ibn Abi Talib: it can only go to [the Imam's] progeny. This was why they rejected the claims of al-Kazim and other brothers of al-Mubarak, as they did that of Muhammad ibn al-Hanafiyya, who, according to them, had falsely claimed the Imamate in rivalry with Ali ibn al-Husayn Zayn al-Abidin. At any rate, it is clear that the Mubarakiyya had come into existence in Isma'il's lifetime and they were originally his supporters. It may safely be assumed that Mubarakiyya was one of the original name of the nascent Isma'ilism, as well as the regional identifications of the followers of al-Mubarak, who, on the whole, merged into the main fold of Isma'ilism in the time of Muhammad ibn Isma'il. Al-Nawbakhti, who is best informed about this period, says that the group which supported Muhammad was called the Mubarakiyya after al-Mubarak who was a client, or mawla, of Isma'il. Ivanov has shown that al-Mubarak was the epithet of Isma'il himself, on the basis of some passages from the famous Isma'ili da'i of the 4th/10th century,
Abu Ya'qub al-Sijistani, as well as other sources. == Death ==