Based on the Arabic version, Subh Azal added twenty eight units to the Persian Bayan

The Arabic Bayan, written at the same time period as the Persian version, and with identical structure, was completed up to end of the unit 11. Based on the Arabic version, Subh Azal added twenty eight units to the Persian Bayan which brought it to the end of unit 11. He left the rest incomplete for the time of glory (izza), as the Bab have requested. Baha’ullah’s Iqan and later Aqdas are both viewed by the early Baha'is as addendum to the Bayan.

(Abbas Amanat, Religious Texts in Iranian Languages: Symposium Held in Copenhagen May 2002)

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