In Greek mythology, Prometheus warned Epimetheus not to accept Zeus's gift of Pandora.
Prometheus was a Titan famed for stealing fire from the gods and giving it to humanity. Zeus responded by arranging a punishment for humans and by creating Pandora, whom he sent to Epimetheus as a gift. Because Prometheus was associated with foresight, he recognized the danger and advised his brother to reject anything from Zeus.
Epimetheus did not follow the warning. He accepted Pandora, and the story then moves to the opening of the vessel that released suffering into the human world. The contrast between the brothers' names and actions is important: Prometheus represents thinking ahead, while Epimetheus is linked with understanding after an event has happened.
The warning is sometimes omitted from short modern retellings, which can make Pandora's arrival seem unconnected to Prometheus. In the broader myth, however, his theft of fire and his warning form the immediate background to the episode.