Al-Qaeda has reportedly urged fellow extremist organization ISIS, also known as the Islamic State, to release their latest British hostage Alan Henning from captivity, International Business Times reported. Henning was identified as the next ISIS victim at the end of the beheading video of British aid worker David Haines released Saturday.

Al-Qaeda, who frequently criticizes ISIS's extreme methods, has appealed for the Sunni insurgent group to free innocent Henning since he was helping Syrian refugees by delivering medical supplies. But the Islamic State was purportedly obstinate, claiming that the 47-year-old would be beheaded if the UK government did not scale down its anti-ISIS measures in Iraq, further hinting that Henning was a spy.

Henning, a taxi driver from northwest England whom friends describe as a "big man with a big heart," reportedly left his wife of 23 years, Barbara, 45, and two teenage children at home in Salford, Greater Manchester, last Christmas to join a group of Muslim friends, the Guardian reported. They were planning a 20-vehicle, 4,000-mile journey to Syria to deliver medical supplies to refugees caught up in the country's civil war, The Bolton News reported.

On Dec. 26, masked gunmen reportedly stopped the convoy after it crossed the Turkish border and targeted Henning, separating him from the group, ABC News reported.

"He is the nicest of nice guys who has done so much to help other people," fellow taxi driver Kasim Jameel told the newspaper. "He is just a normal bloke, an everyday taxi driver who wanted to do good. We are thinking about him all the time and praying that he will be allowed home to his family."

"He was taking over old ambulances, just helping out as much as he could," a close friend told the Telegraph newspaper. "There were a few of them that went out with him. They were just a group of mates that started it all off. They were supposed to be over there for about six months, but he was kidnapped just a few days after he left."

Shortly after Henning was kidnapped, a representative of Jabhat al-Nusra, the al-Qaeda-front in Syria, reached out to his captors and informed them that their actions are "wrong under Islamic law...and counter-productive," according to a journalist, who interviewed the al-Qaeda-backed representative.

Previously, Henning had reportedly traveled to Syria as part of two similar humanitarian aid convoys organized by the small, informal volunteer group Aid 4 Syria and the UK Arab Society.

While making a documentary about such convoys to Syria, BBC journalist Catrin Nye met Henning and learned about how his first trip to Syria had driven him to do more, she told the Guardian.

"It had been a life-changing experience," Nye said. "He had handed out the goods. He described holding the children ... and how that really affected him. He told me he had to go back."

"He loved the cause so much that when he went on holiday with his family, he had a big tattoo across his arm, saying, 'aid for Syria.' He was that dedicated," Jameel told The Bolton News.