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A lost work or a lost title? Iqāma al-ʿIbbur: T-S 10G5.71

Nadia Vidro

T-S 10G5.7 is a Fihrist of Saadya Gaon’s works compiled by his sons Sheʾerit and Dosa about a decade after the Gaon’s death (the fragment itself is a later copy). This unique document, sent upon request from Babylonia to Fusṭāṭ, is important not only because it preserves a list of Saadya’s books but also for its biographical information. It explains that Saadya “lived for just under sixty years [...] of them fourteen years less four days in the academy of Sura” and “died at the end of the middle watch in the night of Monday, 26th Iyyar, year 1253 [of the Seleucid Era]” (16 May 942 CE). These data allowed for the correction of the year of Saadya’s birth and the dating of some of his works about which it had been known only that Saadya composed them at a certain age, e.g. the Refutation of Anan composed at the age of 23 years.

Image of T-S 10G5.7

The fihrist of Saadya's works, T-S 10G5.7


T-S 10G5.7 was published and discussed in a number of publications, by Mann, Malter, Poznanski, Allony and Gil,2 and mentioned in many others. While most books in the Fihrist of Saadya’s works have now been identified, some remain unknown. One of the titles that does not appear anywhere else is Iqāma al-ʿIbbur, a work clearly related to calendar. This title is mentioned among other polemical treatises, which led Poznanski to suggest that it was a polemic against the Qaraites on the antiquity of the calendar.3 The perception of the book as a polemic is also reflected in Allony’s translation of the title as The Proof of the Calendar (הוכחת העיבור).4 Stern argued that this was a mistranslation and corrected it to The Setting of the Calendar, implying that it was a technical treatise on how to set the calendar.

To help clarify the nature of this work, I would like to suggest a new reading of the two lines of T-S 10G5.7 that refer to Iqāma al-ʿIbbur. Unfortunately, these lines are damaged and require a reconstruction.


T-S 10G5.7 verso snippet

T-S 10G5.7 verso snippet of the last two lines of text on the page


These lines were read by Mann as:6

וכתאב גמע אלחגה ללסורוג וכתאב אל[גמ]ע אבטאל

אל.....יה ואקאמת אלעיבור וכתאב אל[וגוב? א]לצלאת

The reading was corrected by Allony to:7

וכתאב גמע אלחגה ללסראג וכתב8 אל[ ] אבטאל

אל[   ]יה ואקאמת אלעיבור וכתאב אל[וגוב א]לצלאת

The underlined words וכתאב אל[ ] אבטאל אל[ ]יה ואקאמת אלעיבור were understood by previous researchers as referring to two separate titles: a book against analogy Kitāb Ibṭāl al-Qiyās and a book on calendar Iqāma al-ʿIbbur. However, this reading does not fit well with the remains of the letters preserved in the fragment. Besides, it creates an oddity: all titles of what Sheʾerit and Dosa call “composed books” (i.e. not Bible commentaries) begin with the word kitāb “a book”, or, in the case of a commentary on Sefer Yeṣira, tafsīr “a commentary”. Iqāma al-ʿIbbur is the only title that does not have any such identifier. I would like to suggest that this is because the word iqāma is not the beginning of the title. Rather, the entire underlined phrase should be regarded as one single title and reconstructed as:

כתאב אלח[גה12  פי13] אבטאל

אל[רו]יה ואקאמה אלעיבור

i.e The Book of Proofs that Invalidate [the Setting of the Calendar by] Lunar Observation and Establish the ʿIbbur.

This reconstruction of the title makes it clear that it was a polemical rather than a technical treatise on the calendar. But it also raises questions. Was The Book of Proofs that Invalidate [the Setting of the Calendar by] Lunar Observation and Establish the ʿIbbur the same work as Distinction of the True from the False Method of Setting Festivals, the full title of Saadya’s most extensive work of calendar polemic, better known as Kitāb al-Tamyīz (The Book of Distinction)?14 There are certain indications that this is a viable conjecture. Firstly, Kitāb al-Tamyīz does not appear in the list. Secondly, there are some parallels in the wording of the titles. The title in T-S 10G5.7 refers to invalidating lunar observation as a calendation method (ibṭāl al-ruʾya) whereas the full title of Kitāb al-Tamyīz mentions the false method of setting festivals (maḏhab [...] al-bāṭil). Thirdly, the title in T-S 10G5.7 fits very well the contents of Kitāb al-Tamyīz, where Saadya considers various methods for setting the calendar (most based on observation) and refutes all except the Rabbanite ʿibbur calculation.15 On the other hand, the title Kitāb al-Tamyīz is well established in manuscripts of the work itself,16 in quotations in Rabbanite and Qaraite sources17 and in book lists.18 Until new evidence comes to light, it will be impossible to resolve the question of the two titles.



1  This FOTM was written in the framework of the project “Saadya Gaon’s works on the Jewish calendar: Near Eastern sources and transmission to the West”, which is a collaboration between UCL, London and LMU, Munich, and is funded by the Fritz Thyssen Foundation.

2  J. Mann, “A Fihrist of Sa’adya’s Works,” The Jewish Quarterly Review 11/ 4 (1921): 423–428; H. Malter, Saadia Gaon: His Life and Works, Philadelphia: Jewish Publication Society of America, 1921, pp. 421–428; S. Poznanski, “A Fihrist of Saadya’s Works,” The Jewish Quarterly Review 13/4 (1923), pp. 369–396; N. Allony, The Jewish Library in the Middle Ages: Book Lists from the Cairo Genizah (edited by M. Frenkel, H. Ben-Shammai, with the participation of M. Sokolow), Jerusalem: Ben-Zvi Institute, 2006, no. 85, pp. 312–314; M. Gil, In the Kingdom of Ishmael, Tel-Aviv: Tel-Aviv University, 1997, no. 9, vol. 2, pp. 30–31 (Gil published only the first nine lines of the fragment).

3  Poznansky “A Fihrist of Saadya’s Works,” p. 395.

4  Allony, The Jewish Library, p. 313, l. 24.

5  S. Stern, The Jewish Calendar Controversy of 921/2 CE, Leiden, Boston: Brill, 2019, p. 97 and n.34.

6  Mann, “A Fihrist of Sa’adya’s Works,” p. 425, ll. 23–24; diacritics added by Mann are not represented.

7  Allony, The Jewish Library, p. 313, ll. 23–24.

8  Read וכתאב

9  Mann, p. 428 (items t, v). Poznanski, p. 395 (items 2 and 3). Allony, p. 314 (notes on lines 23–24, 24).

10  Allony, The Jewish Library, p. 313, ll. 20–24.

11  I am grateful to Dr. Moshe Lavee for discussing this reconstruction with me at the recent SJAS conference in Munich (31 July–3 August 2023).

12  For the reconstruction אלחגה, cf. the previous title וכתאב גמע אלחגה ללסראג (note that the word גמע may be marked as deleted).

13  The alternative reconstruction, לאבטאל, seems a worse fit for the ink remains. 

14  This title is recorded in a book list preserved in T-S Misc.36.149: תמייז מדהב אלחק מן אלבאטל פי אתבאת אלאעיאד (Allony, The Jewish Library, no. 31, p. 122, ll. 139–141).

15  It was previously assumed that Kitāb al-Tamyīz was a comprehensive work of anti-Qaraite polemics covering all standard topics of the Rabbanite-Qaraite debate (S. Poznanski, “The Anti-Karaite Writings of Saadiah Gaon,” The Jewish Quarterly Review 10/2 (1898), p. 244; Malter, Saadia Gaon, p. 263; R. Brody, The Geonim of Babylonia and the Shaping of Medieval Jewish Culture. New Haven, London: Yale UP, 1998, p. 97). It is now clear that Kitāb al-Tamyīz is a work exclusively on the calendar. I am currently preparing a critical edition and English translation of this work.

16  T-S 8Ka10.2, fol. 3v.

17  Poznanski, “The Anti-Karaite Writings”, pp. 244–252 (other Qaraite sources can be added to Poznanski’s list).

18  Allony, The Jewish Library, p. 501 (index).


Cite this article

Vidro, Nadia. 2023. "A Lost Work or a Lost Title? Iqāma Al-ʿIbbur: T-S 10G5.7." Taylor-Schechter Genizah Research Unit. doi:10.17863/CAM.107299.


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