The Letters of the Living:
"There is one god, Allah, and Mohammed is his prophet," is one of the five pillars of Islam, the cornerstones of the faith. Islam accepts the existence of numerous prophets throughout history, but Mohammed is accepted as both the greatest of the prophets and the last.
The Bab's claims put him on a footing comparable to that of Mohammad, a situation completely contrary to orthodox Islamic belief. While the Babis might have seen themselves as existing within Islam, mainstream Muslims branded the teachings heretical.
Over the next four years, the Bab was in and out of prison several times, then was transferred to increasingly remote areas in the hopes of the new movement dying out in obscurity. Instead, the disciples continued to spread the message, the Bab himself sometimes won over the locals, and in 1848 he wrote a book called the Bayan, which laid out his teachings, including expected behavior for followers.
Among these teachings, the Bab clarified that his revelations were indeed meant to supersede the older Islamic laws.
In 1848, the new Iranian Shah focused on rooting out the Babi heresy. The Bab was put on trial, and Muslim clerics demanded he explain his teachings, provide proof of his divine mandate, and recant his claims.
Since the government requested a lenient sentence due to the Bab's popularity, the main purpose of the trial may have been to embarrass the Bab. The clerics called for his execution so long as he was sane, and the Crown Prince's physician conveniently found him incompetent. His sentence was commuted to subjection to bastinado, which involves beating the bare soles of the feet, plus continued incarceration.