Abu Dawud Book 36, Hadith Number 5117.

Chapter : Not known.

Narated By Abdullah ibn Abbas : The Prophet (PBUH) wrote a letter to Heraclius: “From Muhammad, the Apostle of Allah, to Hiraql (Heraclius), Chief of the Byzantines. Peace be to those who follow the guidance.” Ibn Yahya reported on the authority of Ibn Abbas that AbuSufyan said to him: We then came to see Hiraql (Heraclius) who seated us before him. He then called for the letter from the Apostle of Allah (PBUH). Its contents were: “In the name of Allah, the Compassionate, the Merciful, from Muhammad the Apostle of Allah, to Hiraql, chief of Byzantines. Peace be to those who follow the guidance. To proceed.”