The Báb revealed Sahifiyi-i-Baynu’l-Haramayn [“The Epistle between the Two Shrines”] in response to questions raised by Mirza Muhit-i-Kirmani’s

Mírzá Muhit responded to the invitation of the Báb and submitted to Him his questions. Pleading the necessity of his immediate departure for Medina, he expressed the hope of receiving, ere his departure from that city, the text of the promised reply. “I will grant your request,” the Báb assured him. On My way to Medina I shall, with the assistance of God, reveal My answer to your questions. If I meet you not in that city, My reply will surely reach you immediately after your arrival at Karbilá. Whatever justice and fairness may dictate, the same shall I expect you to fulfil. ‘If ye do well, to your own behoof will ye do well: and if ye do evil, against yourselves will ye do it.’ ‘God is verily independent of all His creatures.’” [Verses of the Qur’án] 

Mírzá Muhit, ere his departure, again expressed his firm resolve to redeem his solemn pledge. “I shall never depart from Medina,” he assured the Báb, “whatever may betide, until I have fulfilled my covenant with You.” As the mote which is driven before the gale, he, unable to withstand the sweeping majesty of the Revelation proclaimed by the Báb, fled in terror from before His face. He tarried awhile in Medina and, faithless to his pledge and disregardful of the admonitions of his conscience, left for Karbilá.

The Báb, faithful to His promise, revealed, on His way from Mecca to Medina, His written reply to the questions that had perplexed the mind of Mírzá Muhit, and gave it the name of Sahifiyi-i-Baynu’l-Haramayn. Mírzá Muhit, who received it in the early days of his arrival in Karbilá, remained unmoved by its tone and refused to recognise the precepts which it inculcated. His attitude towards the Faith was one of concealed and persistent opposition. At times he professed to be a follower and supporter of that notorious adversary of the Báb, Ḥájí Mírzá Karím Khán, and occasionally claimed for himself the station of an independent leader. 

(Chapter 7, ‘The Dawn-Breakers’)