In Jewish tradition, the usual maximum period said for a soul to remain in Gehinnom is twelve months.
Rabbinic Jewish sources describe Gehinnom as a place or process of punishment and purification after death. A widely cited teaching says that the punishment of ordinary sinners lasts no longer than twelve months. This idea is associated with passages in the Mishnah and Talmud and helps explain why some Jewish mourning and memorial practices are limited to eleven months rather than a full year.
The teaching is not a universal description of every soul. Rabbinic literature distinguishes among different kinds of wrongdoing, and some categories are described as receiving more severe or enduring punishment. Other Jewish thinkers have treated Gehinnom more metaphorically, spiritually, or philosophically.
Gehinnom is therefore not precisely equivalent to the popular Christian image of an eternal hell. Its name derives from the Valley of Hinnom near Jerusalem, a place that became associated with judgment in Jewish scripture and later tradition.