Mahomet in fact began his public career as a simple preacher. The resistance he met with at home, and the necessity of relying for self-preservation on the swords of the men of Medina, converted him from a prophet to a potentate. The change was not one which he could avoid without sacrificing all chances of success; but it does appear to have exercised an unfortunate influence upon his character. As the governor of Medina he became tyrannical and even cruel. Among the worst features of his life is his conduct to the Jews after his attempts at conciliation had been shown to be fruitless. For instance, a Jewish tribe, the Banu Kaynoka, with whom a treaty of friendship had been concluded, were expelled from Medina. Another tribe of the same religion, the Banu Nadhyr, were blockaded in their quarter, and driven to capitulate, on condition of being allowed to leave Medina with their movable property. On the very day upon which the siege by Abu Sofyân in 627 came to an end, Mahomet blockaded the Banu Koraytza, also Jews, and compelled them to surrender at discretion. All the men, six hundred in number, were put to death, and the women were sold as slaves; a punishment which, even on the supposition that the tribe was hostile to the prophet, was unpardonably severe. In the ensuing year he marched against Chaybar, a town inhabited by Jews, besieged and took it. All the Jews taken in arms were put to death, whereupon the rest surrendered on condition of being permitted to withdraw with their families and their portable goods, exclusive of weapons and the precious metals. Kinana, their leader, was executed, and it is a suspicious circumstance that Mahomet married his widow Cafyya. Nor were these the worst of the prophet's misdeeds. He even stooped to sanction, if not to order, private assassination. Shortly after his victory at Badr, a woman and an old man, both of whom had rendered themselves offensive by their anti-Mussulman verses, were murdered in the night; and in both instances the murderers received the protection and countenance of the prophet and his followers.