The first poetical tale in Thomas Moore's Lalla Rookh.
The Veiled Prophet of Khorassan was Hakim ben Allah, surnamed the Veiled (
Mokanna), founder of an Arabic sect in the eighth century. Having lost an eye, and being otherwise disfigured in battle, he wore a veil to conceal his face, but his followers said it was done to screen his dazzling brightness. He assumed to be a god, and maintained that he had been Adam, Noah, and other representative men. When encompassed by Sultan Mahadi, he first poisoned all his followers at a banquet, and then threw himself into a burning acid, which wholly destroyed his body.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894