Letter to Aaron ha-Ḥazan ben Ephraim
[From:] The son of the exilarch.
The news reached us—our splendorous one, my dear ḥazan, R. Aaron, may God support you—concerning what the person known as Ibn Shā’ūl and his son did, undertaking ritual slaughter that went against established law. They transgressed time after time; even though they were exhorted and warned, these warnings did not concern them. So, we went forth and pronounced a ḥerem [ban] against anyone who speaks with them or does business with them or goes out to the bathhouse with them or gets within four cubits of them. It is necessary to promulgate this ban and to inform the Jewish community—may God defend it—to apply assiduously the excommunication according to the manner described, until [father and son] repent.
Salvation.
Source: JTS ENA 4009.11.
Published in: The Posen Library of Jewish Culture and Civilization, vol. 3: Encountering Christianity and Islam.