Abraham Isaac Kook (1865–1935), the Ashkenazi Chief Rabbi of Mandate Palestine, urged that Jewish settlement of the land should proceed by peaceful means only. Contemporary settler movements follow Kook’s son Tzvi Yehuda Kook (1891–1982), who also did not advocate aggressive conquest. Critics claim that Gush Emunim and followers of Tzvi Yehuda Kook advocate violence based on Judaism's religious precepts. Ian Lustick, Benny Morris, and Nur Masalha assert that radical Zionist leaders relied on religious doctrines for justification for the violent treatment of Arabs in Palestine, citing examples where pre-state Jewish militia used verses from the Bible to justify their violent acts, which included expulsions and massacres such as the one at Deir Yassin.