Actually this is based on Koran 4:92, which forbids Muslims to kill other Muslims. But Infidels are fair game.
"Saudi University Professor Salman Al-Abdali: Suicide Bombings Okay in Tel Aviv, Not in Riyadh," from MEMRITV, October 1 (thanks to Weasel Zippers):
Following are excerpts from an interview with Saudi University professor Salman Al-Abdali, which aired on Iqra TV on October 1, 2009. [...]Someone who blows himself up amidst the enemy is different from someone who blows himself up in a safe place.
Blowing oneself up in Tel Aviv is not like blowing oneself up in Riyadh.
Source: JihadWatch
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