In a discussion of the exact date of the revelation of the Kitab-i-Iqán, attention has been drawn to a letter dated 17 January 1861 written in Baghdad by Haji Mirza Siyyid Muhammad to his son Vakilu'dDawlih. In this letter, Haji Mirza Siyyid Muhammad describes attaining Baha'u'llah's presence. Assuming the accuracy of the date as written, the date of the revelation of the Kitab-i-Iqan can be determined to be just a few days before the writing of the letter, or mid-January 1861. The letter reads in part:
“If you wonder over our state, praised be God and His grace, on the night of the first of Rajab [12 January 1861] we attained the threshold of the Shrines of the twin Imams at Kazimayn.... God willing, the day after next--that is, on the seventh of the month--we will depart this location...
Thank God that one thing I need to write you is that I attained unto the presence of His Holiness Baha [Bahá'u'lláh], upon Him be God's peace.... He showered us with utmost affection and kindness and asked that we stay for the night, and we remained in His presence. The evident truth is that to be deprived of the blessing of His presence is a mighty and evident loss. May God bestow His grace upon me so that I would everlastingly attain unto the blessing of His presence.
- Ahang Rabbani (‘The Conversion of the Great-Uncle of the Bab’; Baha'i Library Online)


