Foremost among the priceless treasures cast forth from the billowing ocean of Bahá’u’lláh’s Revelation ranks the Kitáb-i-Íqán (Book of Certitude), revealed within the space of two days and two nights, in the closing years of that period (1278 A.H.–1862 A.D.). It was written in fulfillment of the prophecy of the Báb, Who had specifically stated that the Promised One would complete the text of the unfinished Persian Bayán, and in reply to the questions addressed to Bahá’u’lláh by the as yet unconverted maternal uncle of the Báb, Hájí Mírzá Siyyid Muhammad, while on a visit, with his brother, Hájí Mírzá Hasan-‘Alí, to Karbilá.
- Shoghi Effendi (‘God Passes By’, chapter 8)