Elder of the Jewish congregation of Berlin in the first quarter of the eighteenth century; court Jew to the crown prince, afterward King Frederick William I. The Jewish community of Berlin was divided into two hostile camps by Magnus' quarrels with his rival, Jost Liebmann. Frederick I. favored the latter, while the crown prince supported Magnus. After the death of Liebmann his widow and sons continued these quarrels, which ended in the victory of Magnus. He induced the members of the congregation to substitute a public synagogue for the two private synagogues hitherto maintained by Liebmann, Veit, and Riess (see
- Geiger, Gesch. der Juden in Berlin, i. 19-21, 38, Berlin, 1871;
- Grätz, Gesch. x. 309-310, 350, Leipsic, 1868.