There are actually two texts in Zoharic literature called Idra: the first being the Idra Rabba, or “greater Idra”, and the second being the Idra Zuta, or “lesser Idra”, with these two texts being intimately connected to each other.
The story of the Idroth is as follows:
Idra Rabba: R. Shim‘on b. Yohai convenes with nine other scholars, and they gather in the sacred אִדְרָא, or threshing field, where they thresh out secrets. Each scholar expounds various configurations of the partsufin, and three of them die in ecstasy while doing so.
Idra Zuta: Years later, at RASHB"I’s deathbed, the seven still-living scholars come to his deathbed, along with the whole heavenly host. He alone explains the configurations of the partsufin, so this work is more unified. RASHB"I wavers between this world and the next.
In the standard printed edition of the Zohar, the Idra Rabba is printed in Naso, and the Idra Zuta is printed in Ha’azinu.
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