Circular, issued by the government of Prussia [Present-day Germany]: “If a Jew is to testify in court but cannot read German, and thus unable to speak the oath himself, a rabbi shall declare to him in court: ‘We take your oath under Adonai, the god of Israel,’ and the testifying Jew shall respond with ‘Amen,’ which completes his oath.”
Koch, Christian Friedrich. Die Juden im Preussischen Staate (The Jews in the State of Prussia). Baumann: Marienwerder (Prussia), 1833. Page 96. Researched by Dominik Jacobs 3/31/2020