The French translation
of the Bayan does not appear to make mention of it (searching for "femme", "bigamie", "polygamie"), nor do I see anything within Selections from the Writings of the Bab
, and as per pp. 24
-25 of God Passes By, the Bayan is one of the few works of the Bab not to suffer from interpolation and corruption:
Within the walls of that same fortress the Bayán (Exposition)-- that monumental repository of the laws and precepts of the new Dispensation and the treasury enshrining most of the Báb's references and tributes to, as well as His warning regarding, "Him Whom God will make manifest"--was revealed. Peerless among the doctrinal works of the Founder of the Bábí Dispensation; consisting of nine Vahíds (Unities) of nineteen chapters each, except the last Vahíd comprising only ten chapters; not to be confounded with the smaller and less weighty Arabic Bayán, revealed during the same period; fulfilling the Muhammadan prophecy that "a Youth from Baní-Háshim ... will reveal a new Book and promulgate a new Law;" wholly safeguarded from the interpolation and corruption which has been the fate of so many of the Báb's lesser works, this Book, of about eight thousand verses, occupying a pivotal position in Bábí literature, should be regarded primarily as a eulogy of the Promised One rather than a code of laws and ordinances designed to be a permanent guide to future generations.
(Shoghi Effendi, God Passes By, pp. 24-25, emphasis added)
The Bab did have one wife and, some sources claim, one concubine (by the time of His youthful death) which perhaps is the source (or motivation) of the accusation.
(References are made to the Bab's second wife, Fatimih, in Covenant of Baha'u'llah
by Adib Taherzadeh, pp. 73-74 and The Revelation of Baha'u'llah,
by Adib Taherzadeh, volume 1, p. 249 and volume 2 p. 262. The latter mentions that the Bab took Fatimih as His second wife, only after "much insistence" by Manuchihr Khan, the Governor of Isfahan.)