written texts in laying down Jewish law. The position of Yehudai Gaon was that applied halakhic rulings could not be made simply by citing halakha from the Tanakh, Mishna, or Talmud. The prescriptive authority of a Jewish law could only be vouchsafed if a living master ruled that it was known to be implemented in practice (halakhah le-ma'aseh). Written aide-mémoires from the oral tradition (nushaot), or from a megilat setarim (sequestered scroll), were devoid of cultural authority since they were not authorized, as were girsaot, by a master of the oral law linked to the chain of tradition. Pirqoi ben Baboi's construal of the relevant sugya in the Talmud is, however, arguably unique in inferring from the conditions set for making halakhah le-ma'aseh the idea that the only valid method for transmitting the Oral Torah must be itself oral. The problem with Palestinian rabbis, in his view, was that in eliciting passages inscribed from the Mishna and Talmud, some of them 'hidden' (genuzin), each imposed their personal interpretation upon them. The Babylonian practice exemplified by Yehudai Gaon was that Talmud legal teachings are validated only if they can be corroborated by living masters familiar with non-textual traditions, the chain of oral judgments, consensus and customary usage. The Greek distinction whose impact is at work in these controversies was transmitted in a similar form to Islamic culture, where, after the establishment of the Qur'an text, there arose fierce opposition, particularly in areas best known for having by heart these stories, such as Basra and Kufa, to the inscription of the accompanying oral traditions. Scholars like Ibn Sa'd (784–845) vehemently argued that Muslims ought not to repeat what Islamic jurists conceived to be the theological error in Judaism, of writing down the Mathnā (i.e. the Mishna). Such practices would only invest teachers with an authority comparable to the foundational text of the Qur'an itself. This hostility to the written, as opposed to oral, recording of what Muhammad was remembered as having said, namely the ḥadīth, prevailed under the Umayyad Caliphate until Umar II (r. 717–720) ordered that an official compendium (tadwīn) of ḥadīth be made. Human memory was frail, and notes (atraf) had been made, but like nushaot, these were to remain secreted away. Gregor Schoeler. analyzing fulminations impugning the Umayyad dynasty's legitimacy, correlated the genre hostile to the inscription of hadith with the fall of the Umayyads. They had broken a