JERUSALEM—Prime Minister Benjamin Netanyahu ordered Israel’s attorney general to open an investigation into Jerusalem’s top Muslim cleric, who called for killing Jews.

Mufti Mohammed Hussein, speaking last week at an event celebrating the 47th anniversary of Palestinian Authority President Mahmoud Abbas’ Fatah movement, cited a traditional text attributed to the Prophet Muhammad that says: “The hour of judgment will not come until you fight the Jews. The Jew will hide behind the stone and behind the tree. The stone and the tree will cry, ‘Oh Muslim, Oh Servant of God, this is a Jew behind me, come and kill him.’ “

Video of the mufti’s speech was posted on YouTube by Palestinian Media Watch; the group’s account was frozen for several days over the content. The video also shows a man introducing the mufti saying that “Our war with the descendants of the apes and pigs is a war of religion and faith. Long live Fatah!”

Netanyahu said Sunday that “These are grave words that the world needs to condemn.”

Hussein told Israel Radio Sunday that he was just quoting the religious text, not calling for the murder of Jews. No Palestinian leader has condemned his words.