There is no such thing in the writings of the Bab just wishful Baha'i thinking.
The Bab mentions the One Whom God will Make Manifest often in the Bayan, the Bab wrote about whom God would make manifest;
"Out of utter nothingness, O great and omnipotent Master, Thou hast, through the celestial potency of Thy might, brought me forth and raised me up to proclaim this Revelation. I have made none other but Thee my trust; I have clung to no will but Thy Will. Thou art, in truth, the All-Sufficing and behind Thee standeth the true God, He Who overshadoweth all things...." Selections from the Writings of the Báb, p. 59.
"..In 1848, only two years before His martyrdom, the Báb revealed the Bayan, the book which was to serve as the principal repository of his laws and the fullest expression of His theological doctrines. Essentially the book is an extended tribute to the coming Promised One, now invariably termed “Him Whom God will make manifest.” The latter designation occurs some 300 times in the book, appearing in virtually every one of its chapters, regardless of their ostensible subject. The Bayan and all it contains depend upon His Will; the whole of the Bayan contains in fact “nought but His mention”; the Bayan is “a humble gift” from its Author to Him Whom God will make manifest; to attain His Presence is to attain the Presence of God. He is “the Sun of Truth,” “the Advent of Truth,” “the Point of Truth,” “the Tree of Truth” (Persian Bayán, unpublished manuscript. References to units and chapters 7.1; 5.7; 4.1; and 7.11. )
The Bab also wrote;
"..I swear by the most holy Essence of God--exalted and glorified be He--that in the Day of the appearance of Him Whom God shall make manifest a thousand perusals of the Bayan cannot equal the perusal of a single verse to be revealed by Him Whom God shall make manifest..." Selections from the Writings of the Báb, p. 104.
Baha'u'llah has thus written;
"Our exalted Herald — may the life of all else besides Him be offered up for His sake — hath revealed certain laws. However, in the realm of His Revelation these laws were made subject to Our sanction, hence this Wronged One hath put some of them into effect by embodying them in the Kitáb-i-Aqdas in different words. Others We set aside. He holdeth in His hand the authority. He doeth what He willeth and He ordaineth whatsoever He pleaseth. He is the Almighty, the All-Praised. There are also ordinances newly revealed. Blessed are they that attain. Blessed are they that observe His precepts." Ishráqát (TB:132)
Regards Tony