Musannaf Ibn Abi Shaybah

Hazrat Hasan bin Salih (may Allah be pleased with him) narrates that I asked Hazrat Ubaidullah bin Umar (may Allah be pleased with him) about the Islam of the people of the wilderness and villages. He replied: Whoever among the people of Sawad became Muslim, if he was a dhimmi (one who had a covenant), the land and wealth remain his. And whoever embraced Islam who had no covenant (no agreement or treaty), and he was conquered by force, then his land belongs to the Muslims. Hazrat Ubaidullah says that this was written in the letter of Hazrat Umar bin Abdul Aziz.