Al-Matalib al-'Aliyah 4284 — The letter of the Prophet ﷺ to Caesar

It is narrated from Abdullah bin Shaddad (may Allah have mercy on him), attributing it to the Prophet (marfu'), that the Messenger of Allah (peace and blessings be upon him) sent a letter to Heraclius, the ruler of Rome, in which was written: "From Muhammad (peace and blessings be upon him), the Messenger of Allah, to Heraclius, the ruler of Rome. I invite you to the religion of Islam. If you accept Islam, you will have the same rights as the Muslims have, and the same duties and responsibilities will be upon you as are upon the Muslims. But if you do not wish to enter Islam, then pay the jizyah, for Allah Almighty says: 'Fight those who do not believe in Allah or in the Last Day, and who do not forbid what Allah and His Messenger have forbidden, and who do not follow the religion of truth, from among those who were given the Book, until they pay the jizyah willingly while they are humbled' [Surah al-Tawbah: 29]. And if you do not accept this either, then do not stand between the peasants, that is, the common subjects, and Islam, so that they may accept Islam or pay the jizyah."
Takhrij: Imam al-Harith bin Abi Usamah narrated it in his Musnad (Bughyat al-Bahith: 647). This narration is mursal, because Abdullah bin Shaddad is a Successor (Tabi'i) and he has reported it directly from the Prophet (peace and blessings be upon him).