Musannaf Ibn Abi Shaybah 22885 — A man who accepts Islam while owning

It is narrated from Hasan (may Allah have mercy on him) that Ubaydullah bin Umar (may Allah have mercy on him) was asked: "If someone from the people of Iraq becomes Muslim, what is the ruling?" He (may Allah have mercy on him) said: "If the one from the people of Iraq who becomes Muslim is under our protection (dhimmah), then his land and his wealth remain his. And if the one who becomes Muslim is not under our protection, on land that we conquered by force (through jihad), then that land will belong to the Muslims." Ubaydullah said: "I read this ruling in a letter of Umar bin Abd al-Aziz (may Allah have mercy on him)."