Prometheus warned his brother Epimetheus not to accept gifts from Zeus in the Pandora myth.
Prometheus is a Titan best known for giving fire to humanity and for suffering Zeus’s punishment afterward. His name is often explained as meaning “forethought,” which contrasts with his brother Epimetheus, whose name is associated with afterthought. That contrast is central to the story.
Prometheus understands that Zeus’s gift may conceal a punishment, so he tells Epimetheus to reject it. Epimetheus ignores the warning and accepts Pandora. The myth then connects Pandora’s opening of the container with the arrival of suffering, illness, toil, and other hardships among humans.
Prometheus does not open the container, and he is not Pandora’s husband. Those roles belong to other parts of the narrative. The warning also explains why Prometheus is portrayed as intellectually cautious while Epimetheus represents learning only after an event has occurred.