Muwatta Imam Malik (Riwayat Yahya)

It is narrated from Hazrat Zuraiq bin Hayan, who was appointed over the revenue office of Egypt during the times of Walid, Sulaiman bin Abdul Malik, and Umar bin Abdul Aziz, that Umar bin Abdul Aziz wrote to him: "Whoever among the Muslims passes by you, then whatever of their wealth is apparent from the trade goods, take from it one dinar out of every forty dinars, that is, the fortieth part. And if it is less than forty dinars, then according to the same calculation up to twenty dinars. If it is even one-third of a dinar less than twenty dinars, then leave that wealth, take nothing from it. And if any non-Muslim under your responsibility passes by you, then from his trade goods take one dinar out of every twenty dinars, and if it is less, then according to the same calculation up to ten dinars. If it is even one-third of a dinar less than ten dinars, then take nothing. And for whatever you take, write a separate receipt for the whole year."