Prophet Muhammad’s (Peace be upon him) letters to Emperor Heraclius, Chosroes II, Muqawqis, Negus, Governor of Syria and Ruler of Bahrain. Late in the six year A.H., on his return from Hudaibiyah, the Prophet Muhammad , decided to send messages to the kings beyond Arabia calling them to Islam. In order to authenticate the credentials of his envoys, a silver seal was made in which were graven the words: "Muhammad the Messenger of Allâh".