The ibbur, Hebrew for "impregnation" or "gestation", is the benevolent counterpart to the dybbuk within the same body of Kabbalistic thought about souls entering a living person: where a dybbuk is an unwilling, often malicious attachment by a soul in distress, an ibbur is a voluntary, temporary union between a righteous departed soul and a living person, undertaken to help the living person complete a task, atone for a shared obligation, or receive spiritual guidance the departed soul is now able to give.
The concept appears in Lurianic Kabbalah, the sixteenth-century mystical system associated with Isaac Luria, as part of a broader theory of how souls interact after death, standing alongside gilgul, the transmigration or reincarnation of a soul into a new body, as one of several distinct ways a soul could relate to the living rather than departing entirely. Unlike the dybbuk, an ibbur is not something a person needs to be freed from; the host is generally understood to consent, consciously or not, and the union is expected to end on its own once its purpose is fulfilled, without any exorcism ritual required.