 He was also known for his oratory and was active in both Kol Jerusalem, the Mandate authorities operated radio station, and Kol Israel, Haganah's illegal radio station, in which he was also an editor.In addition to writing several books, he was also an editor of the "Encyclopedia Hebraica" as an expert on Jerusalem, Zionism, Socialism, and Russian history.A few days before the Provisional State Council's Declaration of Independence of 12 May 1948, he was sent by David Ben-Gurion to Menachem Begin to tell him he and his men would be subject to Ben-Gurion's government, to which Begin consented.