The Kitáb-i-Aqdas - The Most Holy Book
Index term: Claim to Revelation
k37.
Whoso layeth claim to a Revelation direct from God, ere the expiration of a full thousand years, such a man is assuredly a lying impostor. We pray God that He may graciously assist him to retract and repudiate such claim. Should he repent, God will, no doubt, forgive him. If, however, he persisteth in his error, God will, assuredly, send down one who will deal mercilessly with him. Terrible, indeed, is God in punishing! Whosoever interpreteth this verse otherwise than its obvious meaning is deprived of the Spirit of God and of His mercy which encompasseth all created things. Fear God, and follow not your idle fancies. Nay, rather, follow the bidding of your Lord, the Almighty, the All-Wise. Erelong shall clamorous voices be raised in most lands. Shun them, O My people, and follow not the iniquitous and evil-hearted. This is that of which We gave you forewarning when We were dwelling in 'Iráq, then later while in the Land of Mystery, and now from this Resplendent Spot.
n62.
Whoso layeth claim to a Revelation direct from God, ere the expiration of a full thousand years
The Dispensation of Bahá'u'lláh will last until the coming of the next Manifestation of God, Whose advent will not take place before at least "a full thousand years" will have elapsed. Bahá'u'lláh cautions against ascribing to "this verse" anything other than its "obvious meaning", and in one of His Tablets, He specifies that "each year" of this thousand year period consists of "twelve months according to the Qur'án, and of nineteen months of nineteen days each, according to the Bayán".
The intimation of His Revelation to Bahá'u'lláh in the Síyáh-Chál of Tihrán, in October 1852, marks the birth of His Prophetic Mission and hence the commencement of the one thousand years or more that must elapse before the appearance of the next Manifestation of God.
n190.
O source of perversion!
This is a reference to Mírzá Yahyá, known as Subh-i-Azal (Morning of Eternity), a younger half-brother of Bahá'u'lláh, who arose against Him and opposed His Cause. Mírzá Yahyá was nominated by the Báb to serve as a figure-head for the Bábí community pending the imminent manifestation of the Promised One. At the instigation of Siyyid Muhammad-i-Isfahání (see note 192), Mírzá Yahyá betrayed the trust of the Báb, claimed to be His successor, and intrigued against Bahá'u'lláh, even attempting to have Him murdered. When Bahá'u'lláh formally declared His Mission to him in Adrianople, Mírzá Yahyá responded by going to the length of putting forward his own claim to be the recipient of an independent Revelation. His pretensions were eventually rejected by all but a few, who became known as Azalís (see note 177). He is described by Shoghi Effendi as the "Arch-Breaker of the Covenant of the Báb" (see God Passes By, chapter X).
n192.
God hath laid hold on him who led thee astray.
A reference to Siyyid Muhammad-i-Isfahání, who is described by Shoghi Effendi as the "Antichrist of the Bahá'í Revelation". He was a man of corrupt character and great personal ambition who induced Mírzá Yahyá to oppose Bahá'u'lláh and to claim prophethood for himself (see note 190). Although he was an adherent of Mírzá Yahyá, Siyyid Muhammad was exiled with Bahá'u'lláh to 'Akká. He continued to agitate and plot against Bahá'u'lláh. In describing the circumstances of his death, Shoghi Effendi has written in God Passes By:

A fresh danger now clearly threatened the life of Bahá'u'lláh. Though He Himself had stringently forbidden His followers, on several occasions, both verbally and in writing, any retaliatory acts against their tormentors, and had even sent back to Beirut an irresponsible Arab convert, who had meditated avenging the wrongs suffered by his beloved Leader, seven of the companions clandestinely sought out and slew three of their persecutors, among whom were Siyyid Muhammad and Áqá Ján.
The consternation that seized an already oppressed community was indescribable. Bahá'u'lláh's indignation knew no bounds. "Were We", He thus voices His emotions, in a Tablet revealed shortly after this act had been committed, "to make mention of what befell Us, the heavens would be rent asunder and the mountains would crumble." "My captivity", He wrote on another occasion, "cannot harm Me. That which can harm Me is the conduct of those who love Me, who claim to be related to Me, and yet perpetrate what causeth My heart and My pen to groan."