Musannaf Ibn Abi Shayba 9:277

Muhammad ibn Bakr narrated to us, from Ibn Jurayj, who said: Abu Bakr ibn Abdullah informed me, from Muhammad ibn Amr al-Fazari and Yahya ibn Abd al-Rahman ibn Hatib, from Ubayd Allah ibn Abd Allah ibn Utbah, and from Amr ibn Sulaym al-Zuraqi, from Ibn al-Musayyib, and from Abu al-Nasr, from Urwah ibn al-Zubayr, that they said regarding a woman from the People of the Book when she enters from the land of war: If she enters the land of the Arabs under a guarantee of safety (aman), and she demonstrates peacefulness in the land of the Arabs, then there is no harm in a Muslim marrying her. But if she did not demonstrate that except at the time of the marriage proposal, she shall not be married.