Abu Bakr al-Baghdadi (Caliph Ibrahim), the leader of Islamist militant group Isis, has called on Muslims to obey him, in his first video sermon.
Baghdadi has been appointed caliph by the jihadist group, which has seized large swathes of Iraq and Syria.
The video appears to have been filmed on Friday during a sermon at the al-Nouri Mosque in Mosul, northern Iraq.
It surfaced on Saturday amid reports that he had been killed or wounded in an Iraqi air raid.
It was not clear when the attack was supposed to have taken place.
In the sermon, at Mosul's most famous landmark, Baghdadi praised the establishment of the "Islamic state", which was declared by Isis last Sunday.
Experts say the reclusive militant leader has never appeared on video before, although there are photographs of him.
"Appointing a leader is an obligation on Muslims, and one that has been neglected for decades," he said.
He also said that he did not seek out the position of being the caliph, or leader, calling it a "burden".
"I am your leader, though I am not the best of you, so if you see that I am right, support me, and if you see that I am wrong, advise me," he told worshippers.
Shia volunteers have stepped in for the Iraqi army in many parts of northern Iraq following the Isis advance.
Captions in the video referred to Baghdadi as "Caliph Ibrahim", a name he has used since the group unilaterally declared him leader of an "Islamic state" last Sunday.
What is a caliphate?
An Islamic state ruled by a single political and religious leader, or Caliph
Caliphs are regarded by their followers as successors to the Prophet Muhammad and the leader of all Muslims.
First caliphate came into being after Muhammad's death in 632
In the centuries which followed, caliphates had dominion in the Middle East and North Africa.
The last widely accepted caliphate was abolished in 1924 by Turkish leader Kemal Ataturk after the collapse of the Ottoman Empire