(CNN)Since Saudi Arabia executed 47 people in one day, exasperation has poured in from human rights activists and sectarian anger has spread in the Middle East — over the death of one man.

Shia Muslim cleric Nimr al-Nimr was a fervent dissident against the Sunni Muslim Saudi royal family and called for their deposal during the Arab spring uprisings in 2011. He died on Saturday alongside 46 terrorism convicts. Later that night, in predominantly Shia Iran, Molotov cocktails smashed into the Saudi embassy in Tehran. Protesters shouted as it caught fire. Some went inside and ransacked offices.

Police donned riot gear and arrested 40 people. Embassy staff was not present during the fire attack.

Iranian President Hassan Rouhani condemned al-Nimr’s execution in Saudi Arabia, and he also blasted the attack on the Saudi embassy in Tehran and on a Saudi consulate in another Iranian city…[+]