BAGHDAD (AP) — A man purporting to be the leader of the Sunni extremist group that has declared an Islamic state in territory it controls in Iraq and Syria has made what would be his first public appearance, delivering a sermon at a mosque in Iraq’s second-largest city, according to a video posted online Saturday.

The 21-minute video that is said to show Abu Bakr al-Baghdadi, the head of the Islamic State group, was reportedly filmed on Friday at the Great Mosque in the northern city of Mosul. It was released on at least two websites known to be used by the organization and bore the logo of its media arm, but it was not possible to independently verify whether the person shown was indeed al-Baghdadi.

Al-Baghdadi’s purported appearance in Mosul, a city of some 2 million that the militants seized last month, came five days after his group declared the establishment of an Islamic state, or caliphate, in the territories it seized in Iraq and Syria. The group proclaimed al-Baghdadi the leader of its state and demanded that all Muslims pledge allegiance to him.

In the video, the man said to be al-Baghdadi says that “the mujahedeen have been rewarded victory by God after years of jihad, and they were able to achieve their aim and hurried to announce the caliphate and choose the Imam,” referring to the leader.

“It is a burden to accept this responsibility to be in charge of you,” he adds. “I am not better than you or more virtuous than you. If you see me on the right path, help me. If you see me on the wrong path, advise me and halt me. And obey me as far as I obey God.”

Speaking in classical Arabic with little emotion, he outlines a vision that emphasizes holy war, the implementation of a strict interpretation of Islamic law, and the philosophy that the establishment of an Islamic caliphate is a duty incumbent on all Muslims.