Hazrat Aslam (may Allah have mercy on him), who was the freed slave of Hazrat Umar (may Allah be pleased with him), narrates that Hazrat Umar (may Allah be pleased with him) used to stamp a seal on the necks of the dhimmis.

Hazrat Maymun bin Mehran, may Allah have mercy on him, narrates that Hazrat Umar, may Allah be pleased with him, sent Hazrat Hudhaifah bin Yaman, may Allah be pleased with him, and Hazrat Ibn Hunaif, may Allah be pleased with him, with an army. So both of them made the people of the town agree to pay jizya. And both of them said: Whoever among the people of the town does not come and have a seal put on his neck, Allah’s protection is not guaranteed for him.