 On Saturdays and holy days he used to preach in the synagogues, attracting large audiences.Owing to his eloquence Landau was chosen by the communities of Volhynia as member of the rabbinical commission appointed by the emperor in 1861, which necessitated his remaining for five months in St. Petersburg.In 1868 he was called to Vilna as preacher and dayan, which office he held till his death.