Baha'u'llah told some of his close companions that he was himself the return of the Imam Husayn

Baha'u'llah went to the shrine city of Karbala in Iraq, the site of the tomb of the Imam Husayn, where a small but active Babi group existed. He found that it was led by a Sayyid 'Uluvv, who had made claims to being God incarnate. Baha'u'llah faced the man down and convinced him to retract those claims. On the other hand, during his stay in Karbala between August 1851 and March 1852, Baha'u'llah told some of his close companions that he was himself the return of the Imam Husayn, whose return Shi`ites expected after the advent of the Qa'im or Mahdi.

http://www-personal.umich.edu/~jrcole/bahabio.htm