The persistent and decisive intervention of the Russian Minister, Prince Dolgorouki, who left no stone unturned to establish the innocence of Bahá'u'lláh; the public confession of Mulla Shaykh Aliy-i-Turshizi, surnamed Azim, who, in the Siyah-Chal, in the presence of the Hajibu'd-Dawlih and the Russian Minister's interpreter and of the government's representative, emphatically exonerated Him, and acknowledged his own complicity; the indisputable testimony established by competent tribunals; the unrelaxing efforts exerted by His own brothers, sisters and kindred, -- all these combined to effect His ultimate deliverance from the hands of His rapacious enemies. Another potent if less evident influence which must be acknowledged as having had a share in His liberation was the fate suffered by so large a number of His self-sacrificing fellow-disciples who languished with Him in that same prison. For, as Nabil truly remarks, "the blood, shed in the course of that fateful year in Tihran by that heroic band with whom Bahá'u'lláh had been imprisoned, was the ransom paid for His deliverance from the hand of a foe that sought to prevent Him from achieving the purpose for which God had destined Him. (Shoghi Effendi, ‘God Passes By’)
At last, Násiri'd-Dín Sháh agreed to let Bahá'u'lláh go, and decreed that He should be banished from Iran. Bahá'u'lláh had lingered in chains for four agony-laden months. Mirza Aqa Khan sent a confidant named Haji 'Ali to bring Him out of the Siyah-Chal. The sight of the appalling condition of the dungeon and the enfeebled condition of Bahá'u'lláh deeply shocked Haji 'Ali, who assured Bahá'u'lláh that they had had no idea of the terrible circumstances He had endured all those months. Haji 'Ali then offered his own cloak to Bahá'u'lláh, which He refused, preferring to appear before Mirza Aqa Khan and the others of the Government in the rags He was wearing….(H.M. Balyuzi, ‘Baha'u'llah - The King of Glory’)