The phrase “Pharaoh’s hard heart” refers to the biblical story of Pharaoh during the time of Moses in the Book of Exodus. In this story, Pharaoh is described as having a hardened heart, meaning he is stubborn and refuses to let the Israelites go despite a series of plagues that befall Egypt. This hard-heartedness is a central theme in the narrative and is often interpreted as a symbol of obstinacy or resistance to divine will. The story is meant to illustrate themes of power, freedom, and divine intervention.