A tale told to the genie by the fisherman in "The Fisherman and the Jinni."
King Yunan has leprosy and seeks a cure. A sage named Duban, who is skilled in many different sciences but most notably healing, promises he can cure the king. He does so, but one of Yunan's viziers grows jealous and plots to get rid of Duban. He convinces the king that Duban is planning to poison him. The king condemns the protesting sage to death by beheading. Duban finally seems to accept this, and offers the king one of his books of wisdom, telling him to read it while keeping Duban's head nearby.
To everyone's amazement, after the execution, Duban's decapitated head instructs the king to open the book. Yunan opens it but finds the pages blank; the head tells him to continue turning the pages. The pages stick together, so Yunan licks his fingers before turning them. Duban poisoned the pages, and Yunan soon succumbs to the effects and dies.