Payment Quotes - page 4
With regard to the abuse of authority, this also may come about in two ways. First, when what is ordered by an authority is opposed to the object for which that authority was constituted (if, for example, some sinful action is commanded or one which is contrary to virtue, when it is precisely for the protection and fostering of virtue that authority is instituted). In such a case, not only is there no obligation to obey the authority, but one is obliged to disobey it, as did the holy martyrs who suffered death rather than obey the impious commands of tyrants. Secondly, when those who bear such authority command things which exceed the competence of such authority; as, for example, when a master demands payment from a servant which the latter is not bound to make, and other similar cases. In this instance the subject is free to obey or disobey.
Thomas Aquinas
Muhammad Kasim fixed a tax upon all the subjects, according to the laws of the Prophet. Those who embraced the Muhammadan faith were exempted from slavery, the tribute, and the poll-tax, and from those who did not change their creed a tax was exacted according to three grades. The first grade was of great men, and each of these was to pay silver, equal to forty-eight dirams in weight, the second grade twenty-four dirams, and the lowest grade twelve dirams. It was ordered that all who should become Musulmans at once should be exempted from the payment, but those who were desirous of their old persuasion must pay the tribute and poll-tax. Some showed an inclination to abide by their creed, and some having resolved upon paying tribute, held by the faith of their forefathers, but their lands and property were not taken from them...
Muhammad bin Qasim