Final answer:
Zeus sent Iris to instruct King Priam to retrieve Hector's body from Achilles, but the specific directive is not provided in the given text. The details of this storyline are part of the larger narrative within the Iliad, surrounding the human aspects of the Trojan War and the interventions of the gods.
Step-by-step explanation:
In the narrative involving Zeus, Achilles, and Iris, Zeus sent Iris to King Priam of Troy, instructing him to retrieve the body of his son Hector. However, based on the information provided, the specific directive given by Zeus through Iris to King Priam is not stated in the provided context. Amidst Greek mythology and the ancient stories of heroism and divine interventions, Achilles is portrayed as a powerful warrior whose life and destiny were deeply intertwined with the gods and their will. The story of Achilles involves his mother's attempt to protect him, his brief attempt at avoiding war, and his eventual fate connected to his vulnerable heel.
The Iliad, written by Homer, gives a detailed account of Achilles' life, including his role in the Trojan War, his wrath, and his repercussions for his behavior. Considering the general clue that Zeus was displeased with Achilles, it's commonly understood from the epic narrative that Priam was to be guided to secretly enter the Greek camp and respectfully request the return of Hector's body from Achilles. This was part of a series of events illustrating the conflict's humanity and the divine's role in human affairs.