Works and Days contains the fuller account of Pandora opening the jar and releasing evils.
The poem is attributed to Hesiod and is a didactic work about farming, justice, labor, and proper conduct. Within that broader setting, Hesiod tells the story of Pandora as an explanation for why human life includes hardship. The passage describes the jar, its opening, the escape of troubles, and Hope remaining inside.
Hesiod's Theogony also mentions Pandora, but its treatment is shorter and focuses more on divine genealogy and the consequences of Prometheus's actions. The familiar sequence of Pandora, Epimetheus, the jar, and the evils is most completely associated with Works and Days.
The poem is not a novel or a standalone myth collection. Its Pandora episode serves an explanatory and moral purpose within a larger poem about human work and divine justice. That context helps distinguish the source from Homer's Iliad and Odyssey, neither of which supplies the canonical full account.