Editing Umar (section)

=== Free trade ===
Local populations of Jews and Christians, persecuted as religious minorities and taxed heavily to finance the [[Byzantine–Sassanid Wars]], often aided Muslims to take over their lands from the Byzantines and Persians, resulting in exceptionally speedy conquests.{{sfnp|Esposito|2010|p=38}}{{sfnp|Hofmann|2007|p=86}} As new areas were attached to the Caliphate, they also benefited from free trade, while trading with other areas in the Caliphate (to encourage commerce, in Islam trade is not taxed, but wealth is subject to the [[zakat]]).<ref>Islam - An Illustrated History By Greville Stewart Parker Freeman-Grenville, Stuart Christopher Munro-Hay, p. 40</ref> Since the [[Constitution of Medina]], drafted by Muhammad, the Jews and the Christians continued to use their own laws in the Caliphate and had their own judges.<ref>R. B. Serjeant, "Sunnah Jami'ah, pacts with the Yathrib Jews, and the Tahrim of Yathrib: analysis and translation of the documents comprised in the so-called "Constitution of Medina"", Bulletin of the School of Oriental and African Studies (1978), 41: 1–42, [[Cambridge University Press]].</ref><ref>Watt. Muhammad at Medina and R. B. Serjeant "The Constitution of Medina", Islamic Quarterly 8 (1964), p. 4.</ref><ref name="Constitution of Medina">{{cite web |url=https://www.scribd.com/doc/15118390/Madinah-Peace-Treaty |title=Madinah Peace Treaty |via=Scribd}}</ref>