"The unjustly spilled blood of this oppressed martyr will no doubt soon show its effect and divine vengeance will befall Saudi politicians."

That rather ominous quote is from Ayatollah Khamenei who was decidedly upset with Saudi Arabia's execution of prominent Shiite cleric Nimr al-Nimr.

The Sheikh - who died along with three other Shiites and dozens of suspected al-Qaeda operatives in the largest mass execution carried out by Riyadh in 25 years - was a leading voice in Saudi Arabia's anti-government movement. He stood accused of sedition, disobedience and bearing arms for his role in the protests which shook the kingdom's Eastern Province during the Arab Spring. 

News of al-Nimr's death spread through the Muslim world like wildfire on Saturday as protests broke out from Bahrain to Pakistan.