The audio called on “every Muslim in every place” to migrate to lands under Isis' self-declared ‘caliphate’ in Iraq and Syria and fight, or take up arms in the country they live in.
Militants have taken over swathes of both countries after a rapid and bloody insurgency and continue to commit violent atrocities in Isis strongholds. The speech said there is "no excuse for any Muslim who is capable of performing hijrah [migrating] to the Islamic State, or capable of carrying a weapon where he is".
It continues by warning: "Islam was never for a day the religion of peace. Islam is the religion of war.
"Do not think the war that we are waging is the Islamic State’s war alone. Rather, it is the Muslims’ war altogether. It is the war of every Muslim in every place, and the Islamic State is merely the spearhead in this war. It is but the war of the people of faith against the people of disbelief."
Isis supporters were speculating on Thursday that the new release from its media arm al-Furqan would feature Baghdadi, who has not appeared in propaganda for months and has only been seen in public once.
The speech also attacked the rulers of Saudi Arabia, who have led a coalition targeting Houthi rebels in Yemen, accusing them of "lying" and warning the end is "near".
Isis fighters in Iraq captured large parts of Anbar province in April, causing thousands of residents to flee. The sermon took an almost emotive turn when it called on those who fled to return to the area and seek shelter with Isis.
“Specifically our people in al-Anbār, be certain that our hearts are broken on account of your leaving of your homes and your lands, and your seeking of shelter in the territory of the Rāfidah [those who reject Islamic authority] and the Kurdish atheists, and your being forced to wander the lands.
"So return to your lands, and remain in your homes, and seek shelter – after first seeking shelter with Allah – with your people in the Islamic State, for you will find therein, by Allah’s permission, a warm embrace and a safe refuge. For you are our people. We defend you, your honor, and your wealth. We want you to be mighty and noble, we want you to be safe and secure."
A number of reports in recent months claimed Baghdadi was incapacitated by US-led coalition air strikes and temporarily replaced by former physics teacher Abu Alaa Afri.
However, initial claims that Baghdadi was hit in a strike in March were disputed by the Pentagon and analysts were skeptical over whether a self-declared ‘caliph’ would even allow a deputy to serve underneath him.
On Wednesday, the Iraqi ministry of defence claimed Afri had been killed in an air strike targeting a mosque in northern Iraq. A spokesperson for the US coalition later denied it had attacked a mosque, according to the BBC.
Elijah Magnier, the chief correspondent for Al-Rai Media, said the purpose of the audio and its timing was clear: to quell rumours that Baghdadi has been incapacitated and is no longer at the helm of the terror group.
Mr Magnier told The Independent that Isis also clearly needs more fighters for the battlefield. He said this call for recruits followed a document released earlier by Isis that highlighted its need for reinforcements on the battlefield - particularly for suicide bombers.
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