Al-Muwatta Hadith 17.46

Yahya related to me from Malik that he had heard that Umar ibn Abd al-Aziz wrote to his governors telling them to relieve any people who payed the jizya from paying the jizya if they became muslims. Malik said, "The sunna is that there is no jizya due from women or children of people of the Book, and that jizya is only taken from men who have reached puberty. The people of dhimma and the magians do not have to pay any zakat on their palms or their vines or their crops or their livestock. This is because zakat is imposed on the muslims to purify them and to be given back to their poor, whereas jizya is imposed on the people of the Book to humble them. As long as they are in the country they have agreed to live in, they do not have to pay anything on their property except the jizya. If, however, they trade in muslim countries, coming and going in them, a tenth is taken from what they invest in such trade. This is because jizya is only imposed on them on conditions, which they have agreed on, namely that they will remain in their own countries, and that war will be waged for them on any enemy of theirs, and that if they then leave that land to go anywhere else to do business they will haveto pay a tenth. Whoever among them does business with the people of Egypt, and then goes to Syria, and then does business with the people of Syria and then goes to Iraq and does business with them and then goes on to Madina, or Yemen, or other similar places, has to pay a tenth. People of the Book and magians do not have to pay any zakat on any of their property, livestock, produce or crops. The sunna still continues like that. They remain in the deen they were in, and they continue to do what they used to do. If in any one year they frequently come and go in muslim countries then they have to pay a tenth every time they do so, since that is outside what they have agreed upon, and not one of the conditions stipulated for them. This is what I have seen the people of knowledge of our city doing."