“In the Name of Allâh, the Most Beneficent, the Most Merciful.
From Muhammad, the slave of Allâh and His Messenger to Hercules, king of the Byzantines. Blessed are those who follow true guidance. I invite you to embrace Islam so that you may live in security. If you come within the fold of Islam, Allâh will give you double reward, but in case you turn your back upon it, then the burden of the sins of all your people shall fall on your shoulders.
“Say [O Muhammad (Peace be upon him)]: ‘O people of the Scripture (Jews and Christians), come to a word that is just between us and you, that we worship none but Allâh, and that we associate no partners with Him, and that none of us shall take others as lords besides Allâh.’ Then, if they turn away, say: ‘Bear witness that we are Muslims.’ ” [3:64]
The Muslim envoy, Dihyah bin Khalifah Al-Kalbi, was ordered to hand the letter over to king of Busra, who would in turn, send it to Caesar.
Incidentally, Abu Sufyan bin Harb, who by that time had not embraced Islam, was summoned to the court and Hercules asked him many questions about Muhammad (Peace be upon him) and the religion which he preached. The testimony which this avowed enemy of the Prophet gave regarding the personal excellence of the Prophet’s character and the good that Islam was doing the human race, left Hercules wonder-struck.
Read more The Envoy to Caesar, King of Rome