What follows is my provisional translation (in other words, not official or authorized; see here for more) of a Tablet from Baháʼuʼlláh, the original text of which is published in Máʼidiy-i-Ásmání, vol. 4, pp. 90–91.
In a Tablet to Mírzá Áqáy-i-Afnán, the Pen of the Most High—exalted be His glory—hath revealed:
“O people of God! Inquire ye of the people of the Qurʼán: ‘Where is Jábulqá, and what of Jábulsá?  What hath become of those illusory cities?’ They have condemned as a liar that hapless Jaʻfar,  who did not speak falsely. For uttering a single truthful remark, he hath been branded a liar from the early days of Islám to the present time. ‘God’s malison on the head of the people of tyranny!’” 
 cf. Baháʼuʼlláh, Gems of Divine Mysteries, para. 47, note 7: “According to Shíʻih traditions, the twin cities of Jábulqá and Jábulsá are the dwelling place of the Hidden Imám (the Promised One), whence He will appear on the Day of Resurrection.”
 The brother of Imám Ḥasan ʻAskarí, known to Twelver Shíʻihs as “Jaʻfar-i-Kadhdháb” (“Jaʻfar the Liar”). For more information, refer to a similar Tablet from Baháʼuʼlláh: https://adibmasumian.com/translations/existence-of-qaim/
 Qurʼán 11:18.
A scanned version of the complete Persian text of this Tablet appears below.