A manual of Islamic law has this:
As for the captives, the amir [ruler] has the choice of taking the most beneficial action of four possibilities: the first, to put them to death by cutting their necks; the second, to enslave them and apply the laws of slavery regarding their sale and manumission; the third, to ransom them in exchange for goods or prisoners; and fourth, to show favor to them and pardon them. Allah, may he be exalted, says, “When you encounter those [infidels] who deny [Islam] then strike [their] necks” (Qur’an sura 47, verse 4) (Abu’l-Hasan al-Mawardi, The Laws of Islamic Governance).
They didn’t get the ransom, so they beheaded him.
“Jihadi barbarians demanded $100M ransom for Foley’s life,” by Bruce Golding, New York Post, August 20, 2014:
Before bloodthirsty Islamic State militants beheaded James Wright Foley in a gruesome video posted online, the terror thugs demanded a $100 million ransom for the journalist’s safe return, a report said.
The United States refused to pay, according to The New York Times.
It was not clear when the terrorist group made its ransom demand for Foley, who was kidnapped in Syria in 2012, nor is it clear why the US refused, but government sources told the paper that paying such ransoms only helps terror groups.
Several European countries, however, have handed large sums of money to terrorist groups to bring captured citizens home safely.
It was also revealed that US commandos launched a daring raid in Syria to rescue Foley and other American hostages — but the special forces couldn’t find the captives and left empty-handed, officials revealed Wednesday.
President Obama personally approved the elaborate rescue mission earlier this summer. US soldiers gunned down several Islamic State militants and only suffered one minor injury when an aircraft was hit.
“The US government had what we believed was sufficient intelligence, and when the opportunity presented itself, the president authorized the Department of Defense to move aggressively to recover our citizens,” Lisa Monaco, Obama’s top counterterrorism adviser, said in a statement.
“Unfortunately, that mission was ultimately not successful because the hostages were not present.”
The operation was “substantial and complex,” involving multiple branches of the military, helicopters, fixed-wing airplanes and surveillance aircraft, ABC News reported.
The mission, revealed a day after the Islamic State released a gruesome video of Foley’s beheading, marked the first time that US combat forces entered Syria since its bloody civil war erupted three years ago….