BOSTĪ, ABU’L-QĀSEM ESMĀʿĪL b. Aḥmad JĪLĪ, Muʿtazilite and Zaydī author of the late 4th/10th and early 5th/11th century. Little is known about his life. He or his family presumably came from Bost in Sīstān. He seems, however, to have lived for some time, probably in his youth, in eastern Gīlān where he became a follower of the Zaydī legal school of al-Nāṣer le’l-­Ḥaqq (d. 304/917) prevalent there. Some time before 389/999 he became a pupil of the prominent Muʿtazilite theologian ʿAbd-al-Jabbār b. Aḥmad Hamadānī in Ray. In that year he accompanied his teacher on a pilgrimage to Mecca and on their return stayed with him for some time in Baghdad. There he engaged in theological disputation with the Asḥʿarite Abū Bakr Moḥammad Bāqelllānī since ʿAbd-al-Jabbār thought it beneath his dignity to dispute with the latter. Between 403/1012 and 411/1020-21 he came from Ray to Āmol at a time of friction between the Sunnite and Zaydī communities in the town. He provoked Sunnite rioting when he, asked on the day of Ḡadīr Ḵomm about the merits of Abū Bakr and ʿAlī, compared the latter to a new, untouched jug and the former to a jug in which there had been wine, blood, filth, and dirt before it was cleansed, since Abū Bakr, unlike ʿAlī, had been a polytheist for forty years before Islam. After three days he was expelled from Āmol by Ebn Sayf Dīnavarī, governor under the Ziyarid Manūčehr b. Qābūs (Ḥosām-al-Dīn ʿAlī Mo­ḥallī Hamadānī, al-Ḥadāʾeq al-wardīya fī deḵr aʿemmat al-Zaydīya, in Madelung, Arabic Texts, pp. 289-90). He evidently returned to Ray where he was present at the funeral of ʿAbd-al-Jabbār in 415/1024-25 (Aḥmad b. Saʿd-al-Dīn Meswarī, Toḥfat al-abrār, mss. Vienna, Glaser 12, and Ambros. F 279, quoting Abū Yūsof ʿAbd-al-Salām Qazvīnī). The date of his death is given by Jondārī, a late source, as about 420/1029. Jondārī’s assertion that he was a companion of Imam al-­Moʾayyed Beʾllāh and a transmitter of his legal doctrine known in Zaydī legal literature as al-ostāḏ is erroneous and rests on a confusion with Abu’l-Qāsem b. Tāl Ostāḏ Hawsamī. Ebn Šahrāšūb refers to him as the qāżī Abu’l-­Qāsem Bostī.

Works. The following are extant in manuscript: 1. Men kašf asrār al-Bāṭenīya wa ḡawār maḏhabehem, an extract from a refutation of Ismaʿilism fragmentarily preserved (ms. Ambros. Griffin 41). It appears to be written about 400/1009-10 and contains valuable quotations from Ismaʿili works, especially the lost Ketāb al-­maḥṣūl of Moḥammad b. Aḥmad Nasafī. 2. Ketāb al-­baḥṯ ʿalā adellat al-takfīr wa’l-tafsīq, a discussion of the criteria for considering heretical beliefs, especially those at variance with the Muʿtazilite doctrines of God’s unity and justice, as unbelief or grave sin. The book also contains a section on the status of the early caliphs and the opponents of ʿAlī from the Zaydī point of view. It was probably written after 415/1024-25 since ʿAbd-al-­Jabbār is mentioned with the formula raḥemahoʾllāh. (A large portion missing in the fragmentary Berlin ms. [see Stern, p. 19] is contained in the Leiden ms. Or 2973A.) Jondārī mentions the further works: 3. al-­Mūjaz, on theology. Bostī seems to have written a commentary on it which is quoted in the annotation to a copy of the Ketāb al-ebāna of Abū Jaʿfar Hawsamī (ms. Tehran, Majles 235 Ḵᵛoʾī). 4. Ketāb al-marāteb fī manāqeb ahl al-bayt, on the virtues of the family of the Prophet. It is quoted by Moḥallī (al-Ḥadāʾeq, in Made­lung, Arabic Texts, p. 253) with reference to Imam al-­Mahdī le-Dīn Allāh b. al-Dāʿī (d. 359/970). Ebn Šah­rāšūb seems to mention it under the name Ketāb al-­darajāt. Rażī-al-Dīn b. Ṭāwūs quotes it in his al-Yaqīn fī emrat Amīr al-Moʾmenīn (Najaf, 1369/1950, pp. 96-97, 202) as Fażāʾel ʿAlī b. Abī Ṭāleb wa marāteb Amīr al-Moʾmenīn. His copy evidently contained only the section on ʿAlī. 5. Ketāb al-bāher, on the legal doctrine of al-Nāṣer le’l-Ḥaqq, quoted in Ketāb sabīl al-rašād elā maʿrefat rabb al-ʿebād of Moḥammad b. Ḥosayn b. Amīr-al-Moʾmenīm (ms. Vienna, Glaser 179). 6. Ketāb al-moʿtamad fi’l-emāma, a book on the imamate accord­ing to Zaydī doctrine, mentioned by Bostī in his Ketāb al-baḥṯ (no. 2).



Ḥākem Jošamī, Šarḥ ʿoyūn al-masāʾel, in ʿAbd-al-Jabbār, Fażl al-eʿtezāl wa ṭabaqāt al-Moʿtazela, ed. F. Sayyed, Tunis, 1974, pp. 385-86.

Ebn Šahrāšūb, Maʿālem al-ʿolamāʾ, ed. ʿA. Eqbāl, Tehran, 1353/1934, p. 129.

Ebn al-Mortażā, Ṭabaqāt al-Moʿtazela, ed. S. Diwald-Wilzer, Wiesbaden, 1961, p. 117.

Aḥmad b. ʿAbd-Allāh Jondārī, Tarājem al-rejāl, at the beginning of ʿAbd-Allāh b. Meftāḥ, al­-Montaqa’l-moḵtār, Cairo, 1332-41/1914-23, p. 7.

E. Griffini, “Die jüngste ambrosianische Sammlung südarabischer Handschriften,” ZDMG 69, 1915, p. 81.

W. Madelung, Arabic Texts Concerning the History of the Zaydī Imāms of Ṭabaristān, Daylamān and Gīlān, Beirut, 1987, pp. 213, 253, 289-90.

S. M. Stern, “Abū’l-Qāsim al-Bustī and his Refutation of Ismāʿīlīsm,” JRAS, 1961, pp. 14-35; repr. in idem, Studies in Early Ismāʿīlīsm, Jerusalem, 1983, pp. 299-320.

Al-ḏarīʿa XX, pp. 289-90.

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(Wilferd Madelung)

Originally Published: December 15, 1989

Last Updated: December 15, 1989

This article is available in print.
Vol. IV, Fasc. 4, pp. 388-389