In a new video released weekend, Mr. Shekau said his group does not consider Mr. Sanusi a true Muslim, and will attack him whenever an opportunity presents itself.
The Emir had earlier issued a call to arms after a series of deadly attacks by suspected Boko Haram militants in Kano.
“Before I start talking to my brothers who believed in me and the religion of Allah not the religion of democracy, not that of western education, those who believed in the religion of the Quran not that of the constitution and not religion of the Emir of Kano Sanusi Lamido Sanusi, Jonathan, Obasanjo, Atiku, Babangida, Obama, Bush, Clinton, but the religion of Allah,” he said.
“Now listen to me Emir of Kano. I am talking to you and only you because of your recent utterances.
“Let me inform you now that you are late, you should know that you are only but the King of Kano, King of Central Bank, King of money, you are only Sanusi Lamido,” he said.
Mr. Shekau denounced the Emir’s religion as religion based on constitution, idol worship and homosexuality.
“Our own government is defined as government of the Allah by the Allah and for the Allah not as you define your own government as the government of the people by the people and for the people,” he said.
Mr. Shekau said his group will fight local vigilantes and hunters, who have successfully crushed the advances of its fighters in some parts of Nigeria’s northeast.
“Emir of Kano Sanusi you are late, that our triumph is just for a period of time so you said. Even your predecessors who are renowned idol worshipers in Islamic history like ‘Abujahal’ could not succeed fighting Islam.
“Yes you can say that our success is for a period of time, because you are a king of Bank and a loyal citizen of his country,” Mr. Shekau said.
The terrorist leader said his members are ready to be slaughter and kill so they can rest in heaven.
“Because you are made the Emir of Kano that is why you got angry and was calling on the Vigilante groups and hunters to attack us. Let me tell you that the hunters and the vigilante groups will fail and you will also fail,” he said.
He condemned all other Islamic sects in the country, calling them pagans.
He said the Izala, Tijjaniyya, Qadiriyya and Shiite Islamic groups are pagans and his group will continue to kill their followers.
He also condemned the government Saudi Arabia saying they will all perish in hell.
“We will kill you people, we will capture hostages and keep selling some.”