Kidnapping infidels and releasing them for ransom or killing them, as well as exchanging them for Muslim prisoners if that option is deemed most advantageous for the Muslims, is fully sanctioned in Islamic law: “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 [the Truth=Islam] then strike [their] necks’ (Qur’an sura 47, verse 4)” — Abu’l-Hasan al-Mawardi, al-Ahkam as-Sultaniyyah (The Laws of Islamic Governance), trans. by Dr. Asadullah Yate, (London), Ta-Ha Publishers Ltd., 1996, p. 192.
“Al-Qaeda chief urges kidnappings of Americans,” Channel NewsAsia, April 26, 2014 (thanks to Kenneth):
DUBAI: Al-Qaeda leader Ayman al-Zawahiri has called in an interview for militants to kidnap Westerners, especially Americans, to exchange them for jihadist captives.
In the second part of an interview with Al-Qaeda media arm As-Sahab, which the US-based SITE monitoring service said a jihadist posted on Twitter, Zawahiri was asked what Muslims should do to free militant prisoners.
“I advise them to capture Westerners and especially the Americans as much as they can, to exchange them for their captives,” he replied.
In the first part of the interview, released on April 19, the Al-Qaeda chief called for unity amid widening divisions with a rival jihadist organisation rooted in the Syrian civil war.
Zawahiri succeeded the late Osama bin Laden as leader of the global terror network in 2011.