Bahá’u’lláh was “forced, for no less than four months, to breathe, in utter darkness, whilst in the company of the vilest criminals and freighted down with galling chains, the pestilential air of the vermin-infested subterranean dungeon of Tihrán”

…was not the Bearer of such a Revelation, at the instigation of Shí’ih ecclesiastics and by order of the Sháh himself forced, for no less than four months, to breathe, in utter darkness, whilst in the company of the vilest criminals and freighted down with galling chains, the pestilential air of the vermin-infested subterranean dungeon of Tihrán—a place which, as He Himself subsequently declared, was mysteriously converted into the very scene of the annunciation made to Him by God of His Prophethood? 

- Shoghi Effendi  (‘The Promised Day Is Come’)