The King Assassinates His Vizier
 

The same book says that Nizam al-Malik was assassinated by instigation of the Sunnis. Then they themselves assassinated the Seljuk Sultan Malik-Shah as well.

History records that Nizam a-Malik was assassinated by a Daylami (Persian) slave adhering to the Batinide sect. Ibn al-Athar narrates a story which points out to Malik-Shah himself as the person who arranged to have Nizam al-Malik killed. As to Malik-Shah, they say that he fell sick and died.^[1]