It is reported from Al-Shaʿbī – Allāh have mercy on him – that he said:
ʿAbdul-Malik [ibn Marwān, the Khalīfah] once sent me to the king of the Romans, and I stayed with him for a number of days. When I wanted to leave, he asked me,Are you from the House of [your] king (his family)?I replied,I am just a man from the Arabs.He gave me a parchment and said,Deliver this to your companion (the Caliph).When ʿAbdul-Malik had read it, he said to me,Do you know what it says?I replied,No.He said,It says in it, I wonder at a people who have made other than this man king over them.I said,By Allāh, if I had known I would not have carried it to you. [The Roman king] only said this because he has not seen you.ʿAbdul-Malik said,Rather, he envied me for having you, and was trying to incite me to kill you.This reached the Roman king; and when it did, he said,I wanted nothing but this.
Ibn Al-ʿImād, Shadharāt Al-Dhahab 2:26